/*
* Copyright (c) 2017, Salvatore Sanfilippo <antirez at gmail dot com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Redis nor the names of its contributors may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include "server.h"
#include "endianconv.h"
#include "stream.h"
#define STREAM_BYTES_PER_LISTPACK 2048
/* Every stream item inside the listpack, has a flags field that is used to
* mark the entry as deleted, or having the same field as the "master"
* entry at the start of the listpack> */
#define STREAM_ITEM_FLAG_NONE 0 /* No special flags. */
#define STREAM_ITEM_FLAG_DELETED (1<<0) /* Entry is delted. Skip it. */
#define STREAM_ITEM_FLAG_SAMEFIELDS (1<<1) /* Same fields as master entry. */
void streamFreeCG(streamCG *cg);
size_t streamReplyWithRangeFromConsumerPEL(client *c, stream *s, streamID *start, streamID *end, size_t count, streamConsumer *consumer);
/* -----------------------------------------------------------------------
* Low level stream encoding: a radix tree of listpacks.
* ----------------------------------------------------------------------- */
/* Create a new stream data structure. */
stream *streamNew(void) {
stream *s = zmalloc(sizeof(*s));
s->rax = raxNew();
s->length = 0;
s->last_id.ms = 0;
s->last_id.seq = 0;
s->cgroups = NULL; /* Created on demand to save memory when not used. */
return s;
}
/* Free a stream, including the listpacks stored inside the radix tree. */
void freeStream(stream *s) {
raxFreeWithCallback(s->rax,(void(*)(void*))lpFree);
if (s->cgroups)
raxFreeWithCallback(s->cgroups,(void(*)(void*))streamFreeCG);
zfree(s);
}
/* Generate the next stream item ID given the previous one. If the current
* milliseconds Unix time is greater than the previous one, just use this
* as time part and start with sequence part of zero. Otherwise we use the
* previous time (and never go backward) and increment the sequence. */
void streamNextID(streamID *last_id, streamID *new_id) {
uint64_t ms = mstime();
if (ms > last_id->ms) {
new_id->ms = ms;
new_id->seq = 0;
} else {
new_id->ms = last_id->ms;
new_id->seq = last_id->seq+1;
}
}
/* This is just a wrapper for lpAppend() to directly use a 64 bit integer
* instead of a string. */
unsigned char *lpAppendInteger(unsigned char *lp, int64_t value) {
char buf[LONG_STR_SIZE];
int slen = ll2string(buf,sizeof(buf),value);
return lpAppend(lp,(unsigned char*)buf,slen);
}
/* This is just a wrapper for lpReplace() to directly use a 64 bit integer
* instead of a string to replace the current element. The function returns
* the new listpack as return value, and also updates the current cursor
* by updating '*pos'. */
unsigned char *lpReplaceInteger(unsigned char *lp, unsigned char **pos, int64_t value) {
char buf[LONG_STR_SIZE];
int slen = ll2string(buf,sizeof(buf),value);
return lpInsert(lp, (unsigned char*)buf, slen, *pos, LP_REPLACE, pos);
}
/* This is a wrapper function for lpGet() to directly get an integer value
* from the listpack (that may store numbers as a string), converting
* the string if needed. */
int64_t lpGetInteger(unsigned char *ele) {
int64_t v;
unsigned char *e = lpGet(ele,&v,NULL);
if (e == NULL) return v;
/* The following code path should never be used for how listpacks work:
* they should always be able to store an int64_t value in integer
* encoded form. However the implementation may change. */
long long ll;
int retval = string2ll((char*)e,v,&ll);
serverAssert(retval != 0);
v = ll;
return v;
}
/* Debugging function to log the full content of a listpack. Useful
* for development and debugging. */
void streamLogListpackContent(unsigned char *lp) {
unsigned char *p = lpFirst(lp);
while(p) {
unsigned char buf[LP_INTBUF_SIZE];
int64_t v;
unsigned char *ele = lpGet(p,&v,buf);
serverLog(LL_WARNING,"- [%d] '%.*s'", (int)v, (int)v, ele);
p = lpNext(lp,p);
}
}
/* Convert the specified stream entry ID as a 128 bit big endian number, so
* that the IDs can be sorted lexicographically. */
void streamEncodeID(void *buf, streamID *id) {
uint64_t e[2];
e[0] = htonu64(id->ms);
e[1] = htonu64(id->seq);
memcpy(buf,e,sizeof(e));
}
/* This is the reverse of streamEncodeID(): the decoded ID will be stored
* in the 'id' structure passed by reference. The buffer 'buf' must point
* to a 128 bit big-endian encoded ID. */
void streamDecodeID(void *buf, streamID *id) {
uint64_t e[2];
memcpy(e,buf,sizeof(e));
id->ms = ntohu64(e[0]);
id->seq = ntohu64(e[1]);
}
/* Compare two stream IDs. Return -1 if a < b, 0 if a == b, 1 if a > b. */
int streamCompareID(streamID *a, streamID *b) {
if (a->ms > b->ms) return 1;
else if (a->ms < b->ms) return -1;
/* The ms part is the same. Check the sequence part. */
else if (a->seq > b->seq) return 1;
else if (a->seq < b->seq) return -1;
/* Everything is the same: IDs are equal. */
return 0;
}
/* Adds a new item into the stream 's' having the specified number of
* field-value pairs as specified in 'numfields' and stored into 'argv'.
* Returns the new entry ID populating the 'added_id' structure.
*
* If 'use_id' is not NULL, the ID is not auto-generated by the function,
* but instead the passed ID is uesd to add the new entry. In this case
* adding the entry may fail as specified later in this comment.
*
* The function returns C_OK if the item was added, this is always true
* if the ID was generated by the function. However the function may return
* C_ERR if an ID was given via 'use_id', but adding it failed since the
* current top ID is greater or equal. */
int streamAppendItem(stream *s, robj **argv, int numfields, streamID *added_id, streamID *use_id) {
/* If an ID was given, check that it's greater than the last entry ID
* or return an error. */
if (use_id && streamCompareID(use_id,&s->last_id) <= 0) return C_ERR;
/* Add the new entry. */
raxIterator ri;
raxStart(&ri,s->rax);
raxSeek(&ri,"$",NULL,0);
size_t lp_bytes = 0; /* Total bytes in the tail listpack. */
unsigned char *lp = NULL; /* Tail listpack pointer. */
/* Get a reference to the tail node listpack. */
if (raxNext(&ri)) {
lp = ri.data;
lp_bytes = lpBytes(lp);
}
raxStop(&ri);
/* Generate the new entry ID. */
streamID id;
if (use_id)
id = *use_id;
else
streamNextID(&s->last_id,&id);
/* We have to add the key into the radix tree in lexicographic order,
* to do so we consider the ID as a single 128 bit number written in
* big endian, so that the most significant bytes are the first ones. */
uint64_t rax_key[2]; /* Key in the radix tree containing the listpack.*/
streamID master_id; /* ID of the master entry in the listpack. */
/* Create a new listpack and radix tree node if needed. Note that when
* a new listpack is created, we populate it with a "master entry". This
* is just a set of fields that is taken as refernce in order to compress
* the stream entries that we'll add inside the listpack.
*
* Note that while we use the first added entry fields to create
* the master entry, the first added entry is NOT represented in the master
* entry, which is a stand alone object. But of course, the first entry
* will compress well because it's used as reference.
*
* The master entry is composed like in the following example:
*
* +-------+---------+------------+---------+--/--+---------+---------+-+
* | count | deleted | num-fields | field_1 | field_2 | ... | field_N |0|
* +-------+---------+------------+---------+--/--+---------+---------+-+
*
* count and deleted just represent respectively the total number of
* entires inside the listpack that are valid, and marked as deleted
* (delted flag in the entry flags set). So the total number of items
* actually inside the listpack (both deleted and not) is count+deleted.
*
* The real entries will be encoded with an ID that is just the
* millisecond and sequence difference compared to the key stored at
* the radix tree node containing the listpack (delta encoding), and
* if the fields of the entry are the same as the master enty fields, the
* entry flags will specify this fact and the entry fields and number
* of fields will be omitted (see later in the code of this function).
*
* The "0" entry at the end is the same as the 'lp-count' entry in the
* regular stream entries (see below), and marks the fact that there are
* no more entires, when we scan the stream from right to left. */
int flags = STREAM_ITEM_FLAG_NONE;
if (lp == NULL || lp_bytes > STREAM_BYTES_PER_LISTPACK) {
master_id = id;
streamEncodeID(rax_key,&id);
/* Create the listpack having the master entry ID and fields. */
lp = lpNew();
lp = lpAppendInteger(lp,1); /* One item, the one we are adding. */
lp = lpAppendInteger(lp,0); /* Zero deleted so far. */
lp = lpAppendInteger(lp,numfields);
for (int i = 0; i < numfields; i++) {
sds field = argv[i*2]->ptr;
lp = lpAppend(lp,(unsigned char*)field,sdslen(field));
}
lp = lpAppendInteger(lp,0); /* Master entry zero terminator. */
raxInsert(s->rax,(unsigned char*)&rax_key,sizeof(rax_key),lp,NULL);
/* The first entry we insert, has obviously the same fields of the
* master entry. */
flags |= STREAM_ITEM_FLAG_SAMEFIELDS;
} else {
serverAssert(ri.key_len == sizeof(rax_key));
memcpy(rax_key,ri.key,sizeof(rax_key));
/* Read the master ID from the radix tree key. */
streamDecodeID(rax_key,&master_id);
unsigned char *lp_ele = lpFirst(lp);
/* Update count and skip the deleted fields. */
int64_t count = lpGetInteger(lp_ele);
lp = lpReplaceInteger(lp,&lp_ele,count+1);
lp_ele = lpNext(lp,lp_ele); /* seek delted. */
lp_ele = lpNext(lp,lp_ele); /* seek master entry num fields. */
/* Check if the entry we are adding, have the same fields
* as the master entry. */
int master_fields_count = lpGetInteger(lp_ele);
lp_ele = lpNext(lp,lp_ele);
if (numfields == master_fields_count) {
int i;
for (i = 0; i < master_fields_count; i++) {
sds field = argv[i*2]->ptr;
int64_t e_len;
unsigned char buf[LP_INTBUF_SIZE];
unsigned char *e = lpGet(lp_ele,&e_len,buf);
/* Stop if there is a mismatch. */
if (sdslen(field) != (size_t)e_len ||
memcmp(e,field,e_len) != 0) break;
lp_ele = lpNext(lp,lp_ele);
}
/* All fields are the same! We can compress the field names
* setting a single bit in the flags. */
if (i == master_fields_count) flags |= STREAM_ITEM_FLAG_SAMEFIELDS;
}
}
/* Populate the listpack with the new entry. We use the following
* encoding:
*
* +-----+--------+----------+-------+-------+-/-+-------+-------+--------+
* |flags|entry-id|num-fields|field-1|value-1|...|field-N|value-N|lp-count|
* +-----+--------+----------+-------+-------+-/-+-------+-------+--------+
*
* However if the SAMEFIELD flag is set, we have just to populate
* the entry with the values, so it becomes:
*
* +-----+--------+-------+-/-+-------+--------+
* |flags|entry-id|value-1|...|value-N|lp-count|
* +-----+--------+-------+-/-+-------+--------+
*
* The entry-id field is actually two separated fields: the ms
* and seq difference compared to the master entry.
*
* The lp-count field is a number that states the number of listpack pieces
* that compose the entry, so that it's possible to travel the entry
* in reverse order: we can just start from the end of the listpack, read
* the entry, and jump back N times to seek the "flags" field to read
* the stream full entry. */
lp = lpAppendInteger(lp,flags);
lp = lpAppendInteger(lp,id.ms - master_id.ms);
lp = lpAppendInteger(lp,id.seq - master_id.seq);
if (!(flags & STREAM_ITEM_FLAG_SAMEFIELDS))
lp = lpAppendInteger(lp,numfields);
for (int i = 0; i < numfields; i++) {
sds field = argv[i*2]->ptr, value = argv[i*2+1]->ptr;
if (!(flags & STREAM_ITEM_FLAG_SAMEFIELDS))
lp = lpAppend(lp,(unsigned char*)field,sdslen(field));
lp = lpAppend(lp,(unsigned char*)value,sdslen(value));
}
/* Compute and store the lp-count field. */
int lp_count = numfields;
lp_count += 3; /* Add the 3 fixed fields flags + ms-diff + seq-diff. */
if (!(flags & STREAM_ITEM_FLAG_SAMEFIELDS)) {
/* If the item is not compressed, it also has the fields other than
* the values, and an additional num-fileds field. */
lp_count += numfields+1;
}
lp = lpAppendInteger(lp,lp_count);
/* Insert back into the tree in order to update the listpack pointer. */
raxInsert(s->rax,(unsigned char*)&rax_key,sizeof(rax_key),lp,NULL);
s->length++;
s->last_id = id;
if (added_id) *added_id = id;
return C_OK;
}
/* Trim the stream 's' to have no more than maxlen elements, and return the
* number of elements removed from the stream. The 'approx' option, if non-zero,
* specifies that the trimming must be performed in a approximated way in
* order to maximize performances. This means that the stream may contain
* more elements than 'maxlen', and elements are only removed if we can remove
* a *whole* node of the radix tree. The elements are removed from the head
* of the stream (older elements).
*
* The function may return zero if:
*
* 1) The stream is already shorter or equal to the specified max length.
* 2) The 'approx' option is true and the head node had not enough elements
* to be deleted, leaving the stream with a number of elements >= maxlen.
*/
int64_t streamTrimByLength(stream *s, size_t maxlen, int approx) {
if (s->length <= maxlen) return 0;
raxIterator ri;
raxStart(&ri,s->rax);
raxSeek(&ri,"^",NULL,0);
int64_t deleted = 0;
while(s->length > maxlen && raxNext(&ri)) {
unsigned char *lp = ri.data, *p = lpFirst(lp);
int64_t entries = lpGetInteger(p);
/* Check if we can remove the whole node, and still have at
* least maxlen elements. */
if (s->length - entries >= maxlen) {
lpFree(lp);
raxRemove(s->rax,ri.key,ri.key_len,NULL);
raxSeek(&ri,">=",ri.key,ri.key_len);
s->length -= entries;
deleted += entries;
continue;
}
/* If we cannot remove a whole element, and approx is true,
* stop here. */
if (approx) break;
/* Otherwise, we have to mark single entries inside the listpack
* as deleted. We start by updating the entries/deleted counters. */
int64_t to_delete = s->length - maxlen;
serverAssert(to_delete < entries);
lp = lpReplaceInteger(lp,&p,entries-to_delete);
p = lpNext(lp,p); /* Seek deleted field. */
int64_t marked_deleted = lpGetInteger(p);
lp = lpReplaceInteger(lp,&p,marked_deleted+to_delete);
p = lpNext(lp,p); /* Seek num-of-fields in the master entry. */
/* Skip all the master fields. */
int64_t master_fields_count = lpGetInteger(p);
p = lpNext(lp,p); /* Seek the first field. */
for (int64_t j = 0; j < master_fields_count; j++)
p = lpNext(lp,p); /* Skip all master fields. */
p = lpNext(lp,p); /* Skip the zero master entry terminator. */
/* 'p' is now pointing to the first entry inside the listpack.
* We have to run entry after entry, marking entries as deleted
* if they are already not deleted. */
while(p) {
int flags = lpGetInteger(p);
int to_skip;
/* Mark the entry as deleted. */
if (!(flags & STREAM_ITEM_FLAG_DELETED)) {
flags |= STREAM_ITEM_FLAG_DELETED;
lp = lpReplaceInteger(lp,&p,flags);
deleted++;
s->length--;
if (s->length <= maxlen) break; /* Enough entries deleted. */
}
p = lpNext(lp,p); /* Skip ID ms delta. */
p = lpNext(lp,p); /* Skip ID seq delta. */
p = lpNext(lp,p); /* Seek num-fields or values (if compressed). */
if (flags & STREAM_ITEM_FLAG_SAMEFIELDS) {
to_skip = master_fields_count;
} else {
to_skip = lpGetInteger(p);
to_skip = 1+(to_skip*2);
}
while(to_skip--) p = lpNext(lp,p); /* Skip the whole entry. */
p = lpNext(lp,p); /* Skip the final lp-count field. */
}
/* Here we should perform garbage collection in case at this point
* there are too many entries deleted inside the listpack. */
entries -= to_delete;
marked_deleted += to_delete;
if (entries + marked_deleted > 10 && marked_deleted > entries/2) {
/* TODO: perform a garbage collection. */
}
/* Update the listpack with the new pointer. */
raxInsert(s->rax,ri.key,ri.key_len,lp,NULL);
break; /* If we are here, there was enough to delete in the current
node, so no need to go to the next node. */
}
raxStop(&ri);
return deleted;
}
/* Initialize the stream iterator, so that we can call iterating functions
* to get the next items. This requires a corresponding streamIteratorStop()
* at the end. The 'rev' parameter controls the direction. If it's zero the
* iteration is from the start to the end element (inclusive), otherwise
* if rev is non-zero, the iteration is reversed.
*
* Once the iterator is initalized, we iterate like this:
*
* streamIterator myiterator;
* streamIteratorStart(&myiterator,...);
* int64_t numfields;
* while(streamIteratorGetID(&myiterator,&ID,&numfields)) {
* while(numfields--) {
* unsigned char *key, *value;
* size_t key_len, value_len;
* streamIteratorGetField(&myiterator,&key,&value,&key_len,&value_len);
*
* ... do what you want with key and value ...
* }
* }
* streamIteratorStop(&myiterator); */
void streamIteratorStart(streamIterator *si, stream *s, streamID *start, streamID *end, int rev) {
/* Intialize the iterator and translates the iteration start/stop
* elements into a 128 big big-endian number. */
if (start) {
streamEncodeID(si->start_key,start);
} else {
si->start_key[0] = 0;
si->start_key[0] = 0;
}
if (end) {
streamEncodeID(si->end_key,end);
} else {
si->end_key[0] = UINT64_MAX;
si->end_key[0] = UINT64_MAX;
}
/* Seek the correct node in the radix tree. */
raxStart(&si->ri,s->rax);
if (!rev) {
if (start && (start->ms || start->seq)) {
raxSeek(&si->ri,"<=",(unsigned char*)si->start_key,
sizeof(si->start_key));
if (raxEOF(&si->ri)) raxSeek(&si->ri,"^",NULL,0);
} else {
raxSeek(&si->ri,"^",NULL,0);
}
} else {
if (end && (end->ms || end->seq)) {
raxSeek(&si->ri,"<=",(unsigned char*)si->end_key,
sizeof(si->end_key));
if (raxEOF(&si->ri)) raxSeek(&si->ri,"$",NULL,0);
} else {
raxSeek(&si->ri,"$",NULL,0);
}
}
si->lp = NULL; /* There is no current listpack right now. */
si->lp_ele = NULL; /* Current listpack cursor. */
si->rev = rev; /* Direction, if non-zero reversed, from end to start. */
}
/* Return 1 and store the current item ID at 'id' if there are still
* elements within the iteration range, otherwise return 0 in order to
* signal the iteration terminated. */
int streamIteratorGetID(streamIterator *si, streamID *id, int64_t *numfields) {
while(1) { /* Will stop when element > stop_key or end of radix tree. */
/* If the current listpack is set to NULL, this is the start of the
* iteration or the previous listpack was completely iterated.
* Go to the next node. */
if (si->lp == NULL || si->lp_ele == NULL) {
if (!si->rev && !raxNext(&si->ri)) return 0;
else if (si->rev && !raxPrev(&si->ri)) return 0;
serverAssert(si->ri.key_len == sizeof(streamID));
/* Get the master ID. */
streamDecodeID(si->ri.key,&si->master_id);
/* Get the master fields count. */
si->lp = si->ri.data;
si->lp_ele = lpFirst(si->lp); /* Seek items count */
si->lp_ele = lpNext(si->lp,si->lp_ele); /* Seek deleted count. */
si->lp_ele = lpNext(si->lp,si->lp_ele); /* Seek num fields. */
si->master_fields_count = lpGetInteger(si->lp_ele);
si->lp_ele = lpNext(si->lp,si->lp_ele); /* Seek first field. */
si->master_fields_start = si->lp_ele;
/* Skip master fileds to seek the first entry. */
for (uint64_t i = 0; i < si->master_fields_count; i++)
si->lp_ele = lpNext(si->lp,si->lp_ele);
/* We are now pointing the zero term of the master entry. If
* we are iterating in reverse order, we need to seek the
* end of the listpack. */
if (si->rev) si->lp_ele = lpLast(si->lp);
} else if (si->rev) {
/* If we are itereating in the reverse order, and this is not
* the first entry emitted for this listpack, then we already
* emitted the current entry, and have to go back to the previous
* one. */
int lp_count = lpGetInteger(si->lp_ele);
while(lp_count--) si->lp_ele = lpPrev(si->lp,si->lp_ele);
/* Seek lp-count of prev entry. */
si->lp_ele = lpPrev(si->lp,si->lp_ele);
}
/* For every radix tree node, iterate the corresponding listpack,
* returning elements when they are within range. */
while(1) {
if (!si->rev) {
/* If we are going forward, skip the previous entry
* lp-count field (or in case of the master entry, the zero
* term field) */
si->lp_ele = lpNext(si->lp,si->lp_ele);
if (si->lp_ele == NULL) break;
} else {
/* If we are going backward, read the number of elements this
* entry is composed of, and jump backward N times to seek
* its start. */
int lp_count = lpGetInteger(si->lp_ele);
if (lp_count == 0) { /* We reached the master entry. */
si->lp = NULL;
si->lp_ele = NULL;
break;
}
while(lp_count--) si->lp_ele = lpPrev(si->lp,si->lp_ele);
}
/* Get the flags entry. */
int flags = lpGetInteger(si->lp_ele);
si->lp_ele = lpNext(si->lp,si->lp_ele); /* Seek ID. */
/* Get the ID: it is encoded as difference between the master
* ID and this entry ID. */
*id = si->master_id;
id->ms += lpGetInteger(si->lp_ele);
si->lp_ele = lpNext(si->lp,si->lp_ele);
id->seq += lpGetInteger(si->lp_ele);
si->lp_ele = lpNext(si->lp,si->lp_ele);
unsigned char buf[sizeof(streamID)];
streamEncodeID(buf,id);
/* The number of entries is here or not depending on the
* flags. */
if (flags & STREAM_ITEM_FLAG_SAMEFIELDS) {
*numfields = si->master_fields_count;
} else {
*numfields = lpGetInteger(si->lp_ele);
si->lp_ele = lpNext(si->lp,si->lp_ele);
}
/* If current >= start, and the entry is not marked as
* deleted, emit it. */
if (!si->rev) {
if (memcmp(buf,si->start_key,sizeof(streamID)) >= 0 &&
!(flags & STREAM_ITEM_FLAG_DELETED))
{
if (memcmp(buf,si->end_key,sizeof(streamID)) > 0)
return 0; /* We are already out of range. */
si->entry_flags = flags;
if (flags & STREAM_ITEM_FLAG_SAMEFIELDS)
si->master_fields_ptr = si->master_fields_start;
return 1; /* Valid item returned. */
}
} else {
if (memcmp(buf,si->end_key,sizeof(streamID)) <= 0 &&
!(flags & STREAM_ITEM_FLAG_DELETED))
{
if (memcmp(buf,si->start_key,sizeof(streamID)) < 0)
return 0; /* We are already out of range. */
si->entry_flags = flags;
if (flags & STREAM_ITEM_FLAG_SAMEFIELDS)
si->master_fields_ptr = si->master_fields_start;
return 1; /* Valid item returned. */
}
}
/* If we do not emit, we have to discard if we are going
* forward, or seek the previous entry if we are going
* backward. */
if (!si->rev) {
int to_discard = (flags & STREAM_ITEM_FLAG_SAMEFIELDS) ?
*numfields : *numfields*2;
for (int64_t i = 0; i < to_discard; i++)
si->lp_ele = lpNext(si->lp,si->lp_ele);
} else {
int prev_times = 4; /* flag + id ms/seq diff + numfields. */
while(prev_times--) si->lp_ele = lpPrev(si->lp,si->lp_ele);
}
}
/* End of listpack reached. Try the next/prev radix tree node. */
}
}
/* Get the field and value of the current item we are iterating. This should
* be called immediately after streamIteratorGetID(), and for each field
* according to the number of fields returned by streamIteratorGetID().
* The function populates the field and value pointers and the corresponding
* lengths by reference, that are valid until the next iterator call, assuming
* no one touches the stream meanwhile. */
void streamIteratorGetField(streamIterator *si, unsigned char **fieldptr, unsigned char **valueptr, int64_t *fieldlen, int64_t *valuelen) {
if (si->entry_flags & STREAM_ITEM_FLAG_SAMEFIELDS) {
*fieldptr = lpGet(si->master_fields_ptr,fieldlen,si->field_buf);
si->master_fields_ptr = lpNext(si->lp,si->master_fields_ptr);
} else {
*fieldptr = lpGet(si->lp_ele,fieldlen,si->field_buf);
si->lp_ele = lpNext(si->lp,si->lp_ele);
}
*valueptr = lpGet(si->lp_ele,valuelen,si->value_buf);
si->lp_ele = lpNext(si->lp,si->lp_ele);
}
/* Stop the stream iterator. The only cleanup we need is to free the rax
* itereator, since the stream iterator itself is supposed to be stack
* allocated. */
void streamIteratorStop(streamIterator *si) {
raxStop(&si->ri);
}
/* Emit a reply in the client output buffer by formatting a Stream ID
* in the standard <ms>-<seq> format, using the simple string protocol
* of REPL. */
void addReplyStreamID(client *c, streamID *id) {
sds replyid = sdscatfmt(sdsempty(),"+%U-%U\r\n",id->ms,id->seq);
addReplySds(c,replyid);
}
/* Send the specified range to the client 'c'. The range the client will
* receive is between start and end inclusive, if 'count' is non zero, no more
* than 'count' elemnets are sent. The 'end' pointer can be NULL to mean that
* we want all the elements from 'start' till the end of the stream. If 'rev'
* is non zero, elements are produced in reversed order from end to start.
*
* If group and consumer are not NULL, the function performs additional work:
* 1. It updates the last delivered ID in the group in case we are
* sending IDs greater than the current last ID.
* 2. If the requested IDs are already assigned to some other consumer, the
* function will not return it to the client.
* 3. An entry in the pending list will be created for every entry delivered
* for the first time to this consumer.
*
* The behavior may be modified passing non-zero flags:
*
* STREAM_RWR_NOACK: Do not craete PEL entries, that is, the point "3" above
* is not performed.
* STREAM_RWR_RAWENTRIES: Do not emit array boundaries, but just the entries,
* and return the number of entries emitted as usually.
* This is used when the function is just used in order
* to emit data and there is some higher level logic.
*
* Note that this function is recursive in certian cases. When it's called
* with a non NULL group and consumer argument, it may call
* streamReplyWithRangeFromConsumerPEL() in order to get entries from the
* consumer pending entires list. However such a function will then call
* streamReplyWithRange() in order to emit single entries (found in the
* PEL by ID) to the client. This is the use case for the STREAM_RWR_RAWENTRIES
* flag.
*/
#define STREAM_RWR_NOACK (1<<0) /* Do not create entries in the PEL. */
#define STREAM_RWR_RAWENTRIES (1<<1) /* Do not emit protocol for array
boundaries, just the entries. */
size_t streamReplyWithRange(client *c, stream *s, streamID *start, streamID *end, size_t count, int rev, streamCG *group, streamConsumer *consumer, int flags) {
void *arraylen_ptr = NULL;
size_t arraylen = 0;
streamIterator si;
int64_t numfields;
streamID id;
/* If a group was passed, we check if the request is about messages
* never delivered so far (normally this happens when ">" ID is passed).
*
* If instead the client is asking for some history, we serve it
* using a different function, so that we return entries *solely*
* from its own PEL. This ensures each consumer will always and only
* see the history of messages delivered to it and not yet confirmed
* as delivered. */
if (group && streamCompareID(start,&group->last_id) <= 0) {
return streamReplyWithRangeFromConsumerPEL(c,s,start,end,count,
consumer);
}
if (!(flags & STREAM_RWR_RAWENTRIES))
arraylen_ptr = addDeferredMultiBulkLength(c);
streamIteratorStart(&si,s,start,end,rev);
while(streamIteratorGetID(&si,&id,&numfields)) {
/* Update the group last_id if needed. */
if (group && streamCompareID(&id,&group->last_id) > 0)
group->last_id = id;
/* Emit a two elements array for each item. The first is
* the ID, the second is an array of field-value pairs. */
addReplyMultiBulkLen(c,2);
addReplyStreamID(c,&id);
addReplyMultiBulkLen(c,numfields*2);
/* Emit the field-value pairs. */
while(numfields--) {
unsigned char *key, *value;
int64_t key_len, value_len;
streamIteratorGetField(&si,&key,&value,&key_len,&value_len);
addReplyBulkCBuffer(c,key,key_len);
addReplyBulkCBuffer(c,value,value_len);
}
/* If a group is passed, we need to create an entry in the
* PEL (pending entries list) of this group *and* this consumer.
* Note that we are sure about the fact the message is not already
* associated with some other consumer, because if we reached this
* loop the IDs the user is requesting are greater than any message
* delivered for this group. */
if (group && !(flags & STREAM_RWR_NOACK)) {
unsigned char buf[sizeof(streamID)];
streamEncodeID(buf,&id);
streamNACK *nack = streamCreateNACK(consumer);
int retval = 0;
retval += raxInsert(group->pel,buf,sizeof(buf),nack,NULL);
retval += raxInsert(consumer->pel,buf,sizeof(buf),nack,NULL);
serverAssert(retval == 2); /* Make sure entry was inserted. */
}
arraylen++;
if (count && count == arraylen) break;
}
streamIteratorStop(&si);
if (arraylen_ptr) setDeferredMultiBulkLength(c,arraylen_ptr,arraylen);
return arraylen;
}
/* This is an helper function for streamReplyWithRange() when called with
* group and consumer arguments, but with a range that is referring to already
* delivered messages. In this case we just emit messages that are already
* in the history of the conusmer, fetching the IDs from its PEL.
*
* Note that this function does not have a 'rev' argument because it's not
* possible to iterate in reverse using a group. Basically this function
* is only called as a result of the XREADGROUP command.
*
* This function is more expensive because it needs to inspect the PEL and then
* seek into the radix tree of the messages in order to emit the full message
* to the client. However clients only reach this code path when they are
* fetching the history of already retrieved messages, which is rare. */
size_t streamReplyWithRangeFromConsumerPEL(client *c, stream *s, streamID *start, streamID *end, size_t count, streamConsumer *consumer) {
raxIterator ri;
unsigned char startkey[sizeof(streamID)];
unsigned char endkey[sizeof(streamID)];
streamEncodeID(startkey,start);
if (end) streamEncodeID(endkey,end);
size_t arraylen = 0;
void *arraylen_ptr = addDeferredMultiBulkLength(c);
raxStart(&ri,consumer->pel);
raxSeek(&ri,">=",startkey,sizeof(startkey));
while(raxNext(&ri) && (!count || arraylen < count)) {
if (end && memcmp(ri.key,end,ri.key_len) > 0) break;
streamID thisid;
streamDecodeID(ri.key,&thisid);
if (streamReplyWithRange(c,s,&thisid,NULL,1,0,NULL,NULL,
STREAM_RWR_RAWENTRIES) == 0)
{
/* Note that we may have a not acknowledged entry in the PEL
* about a message that's no longer here because was removed
* by the user by other means. In that case we signal it emitting
* the ID but then a NULL entry for the fields. */
addReplyMultiBulkLen(c,2);
streamID id;
streamDecodeID(ri.key,&id);
addReplyStreamID(c,&id);
addReply(c,shared.nullmultibulk);
} else {
streamNACK *nack = ri.data;
nack->delivery_time = mstime();
nack->delivery_count++;
}
arraylen++;
}
raxStop(&ri);
setDeferredMultiBulkLength(c,arraylen_ptr,arraylen);
return arraylen;
}
/* -----------------------------------------------------------------------
* Stream commands implementation
* ----------------------------------------------------------------------- */
/* Look the stream at 'key' and return the corresponding stream object.
* The function creates a key setting it to an empty stream if needed. */
robj *streamTypeLookupWriteOrCreate(client *c, robj *key) {
robj *o = lookupKeyWrite(c->db,key);
if (o == NULL) {
o = createStreamObject();
dbAdd(c->db,key,o);
} else {
if (o->type != OBJ_STREAM) {
addReply(c,shared.wrongtypeerr);
return NULL;
}
}
return o;
}
/* Helper function to convert a string to an unsigned long long value.
* The function attempts to use the faster string2ll() function inside
* Redis: if it fails, strtoull() is used instead. The function returns
* 1 if the conversion happened successfully or 0 if the number is
* invalid or out of range. */
int string2ull(const char *s, unsigned long long *value) {
long long ll;
if (string2ll(s,strlen(s),&ll)) {
if (ll < 0) return 0; /* Negative values are out of range. */
*value = ll;
return 1;
}
errno = 0;
*value = strtoull(s,NULL,10);
if (errno == EINVAL || errno == ERANGE) return 0; /* strtoull() failed. */
return 1; /* Conversion done! */
}
/* Parse a stream ID in the format given by clients to Redis, that is
* <ms>.<seq>, and converts it into a streamID structure. If
* the specified ID is invalid C_ERR is returned and an error is reported
* to the client, otherwise C_OK is returned. The ID may be in incomplete
* form, just stating the milliseconds time part of the stream. In such a case
* the missing part is set according to the value of 'missing_seq' parameter.
* The IDs "-" and "+" specify respectively the minimum and maximum IDs
* that can be represented.
*
* If 'c' is set to NULL, no reply is sent to the client. */
int streamParseIDOrReply(client *c, robj *o, streamID *id, uint64_t missing_seq) {
char buf[128];
if (sdslen(o->ptr) > sizeof(buf)-1) goto invalid;
memcpy(buf,o->ptr,sdslen(o->ptr)+1);
/* Handle the "-" and "+" special cases. */
if (buf[0] == '-' && buf[1] == '\0') {
id->ms = 0;
id->seq = 0;
return C_OK;
} else if (buf[0] == '+' && buf[1] == '\0') {
id->ms = UINT64_MAX;
id->seq = UINT64_MAX;
return C_OK;
}
/* Parse <ms>.<seq> form. */
char *dot = strchr(buf,'-');
if (dot) *dot = '\0';
unsigned long long ms, seq;
if (string2ull(buf,&ms) == 0) goto invalid;
if (dot && string2ull(dot+1,&seq) == 0) goto invalid;
if (!dot) seq = missing_seq;
id->ms = ms;
id->seq = seq;
return C_OK;
invalid:
if (c) addReplyError(c,"Invalid stream ID specified as stream "
"command argument");
return C_ERR;
}
/* XADD key [MAXLEN <count>] <ID or *> [field value] [field value] ... */
void xaddCommand(client *c) {
streamID id;
int id_given = 0; /* Was an ID different than "*" specified? */
long long maxlen = 0; /* 0 means no maximum length. */
int approx_maxlen = 0; /* If 1 only delete whole radix tree nodes, so
the maxium length is not applied verbatim. */
int maxlen_arg_idx = 0; /* Index of the count in MAXLEN, for rewriting. */
/* Parse options. */
int i = 2; /* This is the first argument position where we could
find an option, or the ID. */
for (; i < c->argc; i++) {
int moreargs = (c->argc-1) - i; /* Number of additional arguments. */
char *opt = c->argv[i]->ptr;
if (opt[0] == '*' && opt[1] == '\0') {
/* This is just a fast path for the common case of auto-ID
* creation. */
break;
} else if (!strcasecmp(opt,"maxlen") && moreargs) {
char *next = c->argv[i+1]->ptr;
/* Check for the form MAXLEN ~ <count>. */
if (moreargs >= 2 && next[0] == '~' && next[1] == '\0') {
approx_maxlen = 1;
i++;
}
if (getLongLongFromObjectOrReply(c,c->argv[i+1],&maxlen,NULL)
!= C_OK) return;
i++;
maxlen_arg_idx = i;
} else {
/* If we are here is a syntax error or a valid ID. */
if (streamParseIDOrReply(NULL,c->argv[i],&id,0) == C_OK) {
id_given = 1;
break;
} else {
addReply(c,shared.syntaxerr);
return;
}
}
}
int field_pos = i+1;
/* Check arity. */
if ((c->argc - field_pos) < 2 || (c->argc-field_pos % 2) == 1) {
addReplyError(c,"wrong number of arguments for XADD");
return;
}
/* Lookup the stream at key. */
robj *o;
stream *s;
if ((o = streamTypeLookupWriteOrCreate(c,c->argv[1])) == NULL) return;
s = o->ptr;
/* Append using the low level function and return the ID. */
if (streamAppendItem(s,c->argv+field_pos,(c->argc-field_pos)/2,
&id, id_given ? &id : NULL)
== C_ERR)
{
addReplyError(c,"The ID specified in XADD is equal or smaller than the "
"target stream top item");
return;
}
addReplyStreamID(c,&id);
signalModifiedKey(c->db,c->argv[1]);
notifyKeyspaceEvent(NOTIFY_STREAM,"xadd",c->argv[1],c->db->id);
server.dirty++;
/* Remove older elements if MAXLEN was specified. */
if (maxlen) {
if (!streamTrimByLength(s,maxlen,approx_maxlen)) {
/* If no trimming was performed, for instance because approximated
* trimming length was specified, rewrite the MAXLEN argument
* as zero, so that the command is propagated without trimming. */
robj *zeroobj = createStringObjectFromLongLong(0);
rewriteClientCommandArgument(c,maxlen_arg_idx,zeroobj);
decrRefCount(zeroobj);
} else {
notifyKeyspaceEvent(NOTIFY_STREAM,"xtrim",c->argv[1],c->db->id);
}
}
/* Let's rewrite the ID argument with the one actually generated for
* AOF/replication propagation. */
robj *idarg = createObject(OBJ_STRING,
sdscatfmt(sdsempty(),"%U-%U",id.ms,id.seq));
rewriteClientCommandArgument(c,i,idarg);
decrRefCount(idarg);
/* We need to signal to blocked clients that there is new data on this
* stream. */
if (server.blocked_clients_by_type[BLOCKED_STREAM])
signalKeyAsReady(c->db, c->argv[1]);
}
/* XRANGE/XREVRANGE actual implementation. */
void xrangeGenericCommand(client *c, int rev) {
robj *o;
stream *s;
streamID startid, endid;
long long count = 0;
robj *startarg = rev ? c->argv[3] : c->argv[2];
robj *endarg = rev ? c->argv[2] : c->argv[3];
if (streamParseIDOrReply(c,startarg,&startid,0) == C_ERR) return;
if (streamParseIDOrReply(c,endarg,&endid,UINT64_MAX) == C_ERR) return;
/* Parse the COUNT option if any. */
if (c->argc > 4) {
for (int j = 4; j < c->argc; j++) {
int additional = c->argc-j-1;
if (strcasecmp(c->argv[j]->ptr,"COUNT") == 0 && additional >= 1) {
if (getLongLongFromObjectOrReply(c,c->argv[j+1],&count,NULL)
!= C_OK) return;
if (count < 0) count = 0;
j++; /* Consume additional arg. */
} else {
addReply(c,shared.syntaxerr);
return;
}
}
}
/* Return the specified range to the user. */
if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.emptymultibulk)) == NULL
|| checkType(c,o,OBJ_STREAM)) return;
s = o->ptr;
streamReplyWithRange(c,s,&startid,&endid,count,rev,NULL,NULL,0);
}
/* XRANGE key start end [COUNT <n>] */
void xrangeCommand(client *c) {
xrangeGenericCommand(c,0);
}
/* XREVRANGE key end start [COUNT <n>] */
void xrevrangeCommand(client *c) {
xrangeGenericCommand(c,1);
}
/* XLEN */
void xlenCommand(client *c) {
robj *o;
if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.czero)) == NULL
|| checkType(c,o,OBJ_STREAM)) return;
stream *s = o->ptr;
addReplyLongLong(c,s->length);
}
/* XREAD [BLOCK <milliseconds>] [COUNT <count>] STREAMS key_1 key_2 ... key_N
* ID_1 ID_2 ... ID_N
*
* This function also implements the XREAD-GROUP command, which is like XREAD
* but accepting the [GROUP group-name consumer-name] additional option.
* This is useful because while XREAD is a read command and can be called
* on slaves, XREAD-GROUP is not. */
#define XREAD_BLOCKED_DEFAULT_COUNT 1000
void xreadCommand(client *c) {
long long timeout = -1; /* -1 means, no BLOCK argument given. */
long long count = 0;
int streams_count = 0;
int streams_arg = 0;
int noack = 0; /* True if NOACK option was specified. */
#define STREAMID_STATIC_VECTOR_LEN 8
streamID static_ids[STREAMID_STATIC_VECTOR_LEN];
streamID *ids = static_ids;
streamCG **groups = NULL;
int xreadgroup = sdslen(c->argv[0]->ptr) == 10; /* XREAD or XREADGROUP? */
robj *groupname = NULL;
robj *consumername = NULL;
/* Parse arguments. */
for (int i = 1; i < c->argc; i++) {
int moreargs = c->argc-i-1;
char *o = c->argv[i]->ptr;
if (!strcasecmp(o,"BLOCK") && moreargs) {
i++;
if (getTimeoutFromObjectOrReply(c,c->argv[i],&timeout,
UNIT_MILLISECONDS) != C_OK) return;
} else if (!strcasecmp(o,"COUNT") && moreargs) {
i++;
if (getLongLongFromObjectOrReply(c,c->argv[i],&count,NULL) != C_OK)
return;
if (count < 0) count = 0;
} else if (!strcasecmp(o,"STREAMS") && moreargs) {
streams_arg = i+1;
streams_count = (c->argc-streams_arg);
if ((streams_count % 2) != 0) {
addReplyError(c,"Unbalanced XREAD list of streams: "
"for each stream key an ID or '$' must be "
"specified.");
return;
}
streams_count /= 2; /* We have two arguments for each stream. */
break;
} else if (!strcasecmp(o,"GROUP") && moreargs >= 2) {
if (!xreadgroup) {
addReplyError(c,"The GROUP option is only supported by "
"XREADGROUP. You called XREAD instead.");
return;
}
groupname = c->argv[i+1];
consumername = c->argv[i+2];
i += 2;
} else if (!strcasecmp(o,"NOACK")) {
if (!xreadgroup) {
addReplyError(c,"The NOACK option is only supported by "
"XREADGROUP. You called XREAD instead.");
return;
}
noack = 1;
} else {
addReply(c,shared.syntaxerr);
return;
}
}
/* STREAMS option is mandatory. */
if (streams_arg == 0) {
addReply(c,shared.syntaxerr);
return;
}
/* Parse the IDs and resolve the group name. */
if (streams_count > STREAMID_STATIC_VECTOR_LEN)
ids = zmalloc(sizeof(streamID)*streams_count);
if (groupname) groups = zmalloc(sizeof(streamCG*)*streams_count);
for (int i = streams_arg + streams_count; i < c->argc; i++) {
/* Specifying "$" as last-known-id means that the client wants to be
* served with just the messages that will arrive into the stream
* starting from now. */
int id_idx = i - streams_arg - streams_count;
robj *key = c->argv[i-streams_count];
robj *o;
streamCG *group;
/* If a group was specified, than we need to be sure that the
* key and group actually exist. */
if (groupname) {
o = lookupKeyRead(c->db,key);
if (o && checkType(c,o,OBJ_STREAM)) goto cleanup;
if (o == NULL ||
(group = streamLookupCG(o->ptr,groupname->ptr)) == NULL)
{
addReplyErrorFormat(c, "-NOGROUP No such key '%s' or consumer "
"group '%s' in XREADGROUP with GROUP "
"option",
key->ptr,groupname->ptr);
goto cleanup;
}
groups[id_idx] = group;
}
if (strcmp(c->argv[i]->ptr,"$") == 0) {
o = lookupKeyRead(c->db,key);
if (checkType(c,o,OBJ_STREAM)) goto cleanup;
if (o) {
stream *s = o->ptr;
ids[id_idx] = s->last_id;
} else {
ids[id_idx].ms = 0;
ids[id_idx].seq = 0;
}
continue;
} else if (strcmp(c->argv[i]->ptr,">") == 0) {
if (!xreadgroup || groupname == NULL) {
addReplyError(c,"The > ID can be specified only when calling "
"XREADGROUP using the GROUP <group> "
"<consumer> option.");
goto cleanup;
}
ids[id_idx] = group->last_id;
continue;
}
if (streamParseIDOrReply(c,c->argv[i],ids+id_idx,0) != C_OK)
goto cleanup;
}
/* Try to serve the client synchronously. */
size_t arraylen = 0;
void *arraylen_ptr = NULL;
for (int i = 0; i < streams_count; i++) {
robj *o = lookupKeyRead(c->db,c->argv[streams_arg+i]);
if (o == NULL) continue;
stream *s = o->ptr;
streamID *gt = ids+i; /* ID must be greater than this. */
if (s->last_id.ms > gt->ms ||
(s->last_id.ms == gt->ms && s->last_id.seq > gt->seq))
{
arraylen++;
if (arraylen == 1) arraylen_ptr = addDeferredMultiBulkLength(c);
/* streamReplyWithRange() handles the 'start' ID as inclusive,
* so start from the next ID, since we want only messages with
* IDs greater than start. */
streamID start = *gt;
start.seq++; /* uint64_t can't overflow in this context. */
/* Emit the two elements sub-array consisting of the name
* of the stream and the data we extracted from it. */
addReplyMultiBulkLen(c,2);
addReplyBulk(c,c->argv[i+streams_arg]);
streamConsumer *consumer = NULL;
if (groups) consumer = streamLookupConsumer(groups[i],
consumername->ptr,1);
streamReplyWithRange(c,s,&start,NULL,count,0,
groups ? groups[i] : NULL,
consumer, noack);
}
}
/* We replied synchronously! Set the top array len and return to caller. */
if (arraylen) {
setDeferredMultiBulkLength(c,arraylen_ptr,arraylen);
goto cleanup;
}
/* Block if needed. */
if (timeout != -1) {
/* If we are inside a MULTI/EXEC and the list is empty the only thing
* we can do is treating it as a timeout (even with timeout 0). */
if (c->flags & CLIENT_MULTI) {
addReply(c,shared.nullmultibulk);
goto cleanup;
}
blockForKeys(c, BLOCKED_STREAM, c->argv+streams_arg, streams_count,
timeout, NULL, ids);
/* If no COUNT is given and we block, set a relatively small count:
* in case the ID provided is too low, we do not want the server to
* block just to serve this client a huge stream of messages. */
c->bpop.xread_count = count ? count : XREAD_BLOCKED_DEFAULT_COUNT;
/* If this is a XREADGROUP + GROUP we need to remember for which
* group and consumer name we are blocking, so later when one of the
* keys receive more data, we can call streamReplyWithRange() passing
* the right arguments. */
if (groupname) {
incrRefCount(groupname);
incrRefCount(consumername);
c->bpop.xread_group = groupname;
c->bpop.xread_consumer = consumername;
} else {
c->bpop.xread_group = NULL;
c->bpop.xread_consumer = NULL;
}
goto cleanup;
}
/* No BLOCK option, nor any stream we can serve. Reply as with a
* timeout happened. */
addReply(c,shared.nullmultibulk);
/* Continue to cleanup... */
cleanup:
/* Cleanup. */
if (ids != static_ids) zfree(ids);
zfree(groups);
}
/* -----------------------------------------------------------------------
* Low level implementation of consumer groups
* ----------------------------------------------------------------------- */
/* Create a NACK entry setting the delivery count to 1 and the delivery
* time to the current time. The NACK consumer will be set to the one
* specified as argument of the function. */
streamNACK *streamCreateNACK(streamConsumer *consumer) {
streamNACK *nack = zmalloc(sizeof(*nack));
nack->delivery_time = mstime();
nack->delivery_count = 1;
nack->consumer = consumer;
return nack;
}
/* Free a NACK entry. */
void streamFreeNACK(streamNACK *na) {
zfree(na);
}
/* Free a consumer and associated data structures. Note that this function
* will not reassign the pending messages associated with this consumer
* nor will delete them from the stream, so when this function is called
* to delete a consumer, and not when the whole stream is destroyed, the caller
* should do some work before. */
void streamFreeConsumer(streamConsumer *sc) {
raxFree(sc->pel); /* No value free callback: the PEL entries are shared
between the consumer and the main stream PEL. */
sdsfree(sc->name);
zfree(sc);
}
/* Create a new consumer group in the context of the stream 's', having the
* specified name and last server ID. If a consumer group with the same name
* already existed NULL is returned, otherwise the pointer to the consumer
* group is returned. */
streamCG *streamCreateCG(stream *s, char *name, size_t namelen, streamID *id) {
if (s->cgroups == NULL) s->cgroups = raxNew();
if (raxFind(s->cgroups,(unsigned char*)name,namelen) != raxNotFound)
return NULL;
streamCG *cg = zmalloc(sizeof(*cg));
cg->pel = raxNew();
cg->consumers = raxNew();
cg->last_id = *id;
raxInsert(s->cgroups,(unsigned char*)name,namelen,cg,NULL);
return cg;
}
/* Free a consumer group and all its associated data. */
void streamFreeCG(streamCG *cg) {
raxFreeWithCallback(cg->pel,(void(*)(void*))streamFreeNACK);
raxFreeWithCallback(cg->consumers,(void(*)(void*))streamFreeConsumer);
zfree(cg);
}
/* Lookup the consumer group in the specified stream and returns its
* pointer, otherwise if there is no such group, NULL is returned. */
streamCG *streamLookupCG(stream *s, sds groupname) {
if (s->cgroups == NULL) return NULL;
streamCG *cg = raxFind(s->cgroups,(unsigned char*)groupname,
sdslen(groupname));
return (cg == raxNotFound) ? NULL : cg;
}
/* Lookup the consumer with the specified name in the group 'cg': if the
* consumer does not exist it is automatically created as a side effect
* of calling this function, otherwise its last seen time is updated and
* the existing consumer reference returned. */
streamConsumer *streamLookupConsumer(streamCG *cg, sds name, int create) {
streamConsumer *consumer = raxFind(cg->consumers,(unsigned char*)name,
sdslen(name));
if (consumer == raxNotFound) {
if (!create) return NULL;
consumer = zmalloc(sizeof(*consumer));
consumer->name = sdsdup(name);
consumer->pel = raxNew();
raxInsert(cg->consumers,(unsigned char*)name,sdslen(name),
consumer,NULL);
}
consumer->seen_time = mstime();
return consumer;
}
/* Delete the consumer specified in the consumer group 'cg'. The consumer
* may have pending messages: they are removed from the PEL, and the number
* of pending messages "lost" is returned. */
uint64_t streamDelConsumer(streamCG *cg, sds name) {
streamConsumer *consumer = streamLookupConsumer(cg,name,0);
if (consumer == NULL) return 0;
uint64_t retval = raxSize(consumer->pel);
/* Iterate all the consumer pending messages, deleting every corresponding
* entry from the global entry. */
raxIterator ri;
raxStart(&ri,consumer->pel);
raxSeek(&ri,"^",NULL,0);
while(raxNext(&ri)) {
streamNACK *nack = ri.data;
raxRemove(cg->pel,ri.key,ri.key_len,NULL);
streamFreeNACK(nack);
}
raxStop(&ri);
/* Deallocate the consumer. */
raxRemove(cg->consumers,(unsigned char*)name,sdslen(name),NULL);
streamFreeConsumer(consumer);
return retval;
}
/* -----------------------------------------------------------------------
* Consumer groups commands
* ----------------------------------------------------------------------- */
/* XGROUP CREATE <key> <groupname> <id or $>
* XGROUP SETID <key> <id or $>
* XGROUP DELGROUP <key> <groupname>
* XGROUP DELCONSUMER <key> <groupname> <consumername> */
void xgroupCommand(client *c) {
const char *help[] = {
"CREATE <key> <groupname> <id or $> -- Create a new consumer group.",
"SETID <key> <groupname> <id or $> -- Set the current group ID.",
"DELGROUP <key> <groupname> -- Remove the specified group.",
"DELCONSUMER <key> <groupname> <consumer> -- Remove the specified conusmer.",
"HELP -- Prints this help.",
NULL
};
stream *s = NULL;
sds grpname = NULL;
streamCG *cg = NULL;
char *opt = c->argv[1]->ptr; /* Subcommand name. */
/* Lookup the key now, this is common for all the subcommands but HELP. */
if (c->argc >= 4) {
robj *o = lookupKeyWriteOrReply(c,c->argv[2],shared.nokeyerr);
if (o == NULL) return;
s = o->ptr;
grpname = c->argv[3]->ptr;
/* Certain subcommands require the group to exist. */
if ((cg = streamLookupCG(s,grpname)) == NULL &&
(!strcasecmp(opt,"SETID") ||
!strcasecmp(opt,"DELGROUP") ||
!strcasecmp(opt,"DELCONSUMER")))
{
addReplyErrorFormat(c, "-NOGROUP No such consumer group '%s' "
"for key name '%s'",
grpname, c->argv[2]->ptr);
return;
}
}
/* Dispatch the different subcommands. */
if (!strcasecmp(opt,"CREATE") && c->argc == 5) {
streamID id;
if (!strcmp(c->argv[4]->ptr,"$")) {
id = s->last_id;
} else if (streamParseIDOrReply(c,c->argv[4],&id,0) != C_OK) {
return;
}
streamCG *cg = streamCreateCG(s,grpname,sdslen(grpname),&id);
if (cg) {
addReply(c,shared.ok);
} else {
addReplySds(c,
sdsnew("-BUSYGROUP Consumer Group name already exists\r\n"));
}
} else if (!strcasecmp(opt,"SETID") && c->argc == 5) {
} else if (!strcasecmp(opt,"DELGROUP") && c->argc == 4) {
} else if (!strcasecmp(opt,"DELCONSUMER") && c->argc == 5) {
/* Delete the consumer and returns the number of pending messages
* that were yet associated with such a consumer. */
long long pending = streamDelConsumer(cg,c->argv[4]->ptr);
addReplyLongLong(c,pending);
} else if (!strcasecmp(opt,"HELP")) {
addReplyHelp(c, help);
} else {
addReply(c,shared.syntaxerr);
}
}
/* XACK <key> <group> <id> <id> ... <id>
*
* Acknowledge a message as processed. In practical terms we just check the
* pendine entries list (PEL) of the group, and delete the PEL entry both from
* the group and the consumer (pending messages are referenced in both places).
*
* Return value of the command is the number of messages successfully
* acknowledged, that is, the IDs we were actually able to resolve in the PEL.
*/
void xackCommand(client *c) {
streamCG *group;
robj *o = lookupKeyRead(c->db,c->argv[1]);
if (o) {
if (checkType(c,o,OBJ_STREAM)) return; /* Type error. */
group = streamLookupCG(o->ptr,c->argv[2]->ptr);
}
/* No key or group? Nothing to ack. */
if (o == NULL || group == NULL) {
addReply(c,shared.czero);
return;
}
int acknowledged = 0;
for (int j = 3; j < c->argc; j++) {
streamID id;
unsigned char buf[sizeof(streamID)];
if (streamParseIDOrReply(c,c->argv[j],&id,0) != C_OK) return;
streamEncodeID(buf,&id);
/* Lookup the ID in the group PEL: it will have a reference to the
* NACK structure that will have a reference to the consumer, so that
* we are able to remove the entry from both PELs. */
streamNACK *nack = raxFind(group->pel,buf,sizeof(buf));
if (nack != raxNotFound) {
raxRemove(group->pel,buf,sizeof(buf),NULL);
raxRemove(nack->consumer->pel,buf,sizeof(buf),NULL);
streamFreeNACK(nack);
acknowledged++;
}
}
addReplyLongLong(c,acknowledged);
}
/* XPENDING <key> <group> [<start> <stop> <count>] [<consumer>]
*
* If start and stop are omitted, the command just outputs information about
* the amount of pending messages for the key/group pair, together with
* the minimum and maxium ID of pending messages.
*
* If start and stop are provided instead, the pending messages are returned
* with informations about the current owner, number of deliveries and last
* delivery time and so forth. */
void xpendingCommand(client *c) {
int justinfo = c->argc == 3; /* Without the range just outputs general
informations about the PEL. */
robj *key = c->argv[1];
robj *groupname = c->argv[2];
robj *consumername = (c->argc == 7) ? c->argv[6] : NULL;
streamID startid, endid;
long long count;
/* Start and stop, and the consumer, can be omitted. */
if (c->argc != 3 && c->argc != 6 && c->argc != 7) {
addReply(c,shared.syntaxerr);
return;
}
/* Parse start/end/count arguments ASAP if needed, in order to report
* syntax errors before any other error. */
if (c->argc >= 6) {
if (getLongLongFromObjectOrReply(c,c->argv[5],&count,NULL) == C_ERR)
return;
if (streamParseIDOrReply(c,c->argv[3],&startid,0) == C_ERR)
return;
if (streamParseIDOrReply(c,c->argv[4],&endid,UINT64_MAX) == C_ERR)
return;
}
/* Lookup the key and the group inside the stream. */
robj *o = lookupKeyRead(c->db,c->argv[1]);
streamCG *group;
if (o && checkType(c,o,OBJ_STREAM)) return;
if (o == NULL ||
(group = streamLookupCG(o->ptr,groupname->ptr)) == NULL)
{
addReplyErrorFormat(c, "-NOGROUP No such key '%s' or consumer "
"group '%s'",
key->ptr,groupname->ptr);
return;
}
/* XPENDING <key> <group> variant. */
if (justinfo) {
addReplyMultiBulkLen(c,4);
/* Total number of messages in the PEL. */
addReplyLongLong(c,raxSize(group->pel));
/* First and last IDs. */
if (raxSize(group->pel) == 0) {
addReply(c,shared.nullbulk); /* Start. */
addReply(c,shared.nullbulk); /* End. */
addReply(c,shared.nullmultibulk); /* Clients. */
} else {
/* Start. */
raxIterator ri;
raxStart(&ri,group->pel);
raxSeek(&ri,"^",NULL,0);
raxNext(&ri);
streamDecodeID(ri.key,&startid);
addReplyStreamID(c,&startid);
/* End. */
raxSeek(&ri,"$",NULL,0);
raxNext(&ri);
streamDecodeID(ri.key,&endid);
addReplyStreamID(c,&endid);
raxStop(&ri);
/* Consumers with pending messages. */
raxStart(&ri,group->consumers);
raxSeek(&ri,"^",NULL,0);
void *arraylen_ptr = addDeferredMultiBulkLength(c);
size_t arraylen = 0;
while(raxNext(&ri)) {
streamConsumer *consumer = ri.data;
if (raxSize(consumer->pel) == 0) continue;
addReplyMultiBulkLen(c,2);
addReplyBulkCBuffer(c,ri.key,ri.key_len);
addReplyBulkLongLong(c,raxSize(consumer->pel));
arraylen++;
}
setDeferredMultiBulkLength(c,arraylen_ptr,arraylen);
raxStop(&ri);
}
}
/* XPENDING <key> <group> <start> <stop> <count> [<consumer>] variant. */
else {
streamConsumer *consumer = consumername ?
streamLookupConsumer(group,consumername->ptr,0):
NULL;
/* If a consumer name was mentioned but it does not exist, we can
* just return an empty array. */
if (consumername && consumer == NULL)
addReplyMultiBulkLen(c,0);
rax *pel = consumer ? consumer->pel : group->pel;
unsigned char startkey[sizeof(streamID)];
unsigned char endkey[sizeof(streamID)];
raxIterator ri;
mstime_t now = mstime();
streamEncodeID(startkey,&startid);
streamEncodeID(endkey,&endid);
raxStart(&ri,pel);
raxSeek(&ri,">=",startkey,sizeof(startkey));
void *arraylen_ptr = addDeferredMultiBulkLength(c);
size_t arraylen = 0;
while(count && raxNext(&ri) && memcmp(ri.key,endkey,ri.key_len) <= 0) {
streamNACK *nack = ri.data;
arraylen++;
count--;
addReplyMultiBulkLen(c,4);
/* Entry ID. */
streamID id;
streamDecodeID(ri.key,&id);
addReplyStreamID(c,&id);
/* Consumer name. */
addReplyBulkCBuffer(c,nack->consumer->name,
sdslen(nack->consumer->name));
/* Milliseconds elapsed since last delivery. */
mstime_t elapsed = now - nack->delivery_time;
if (elapsed < 0) elapsed = 0;
addReplyLongLong(c,elapsed);
/* Number of deliveries. */
addReplyLongLong(c,nack->delivery_count);
}
raxStop(&ri);
setDeferredMultiBulkLength(c,arraylen_ptr,arraylen);
}
}
/* XCLAIM <key> <group> <consumer> <min-idle-time> <ID-1> <ID-2>
* [IDLE <milliseconds>] [TIME <mstime>] [RETRYCOUNT <count>]
* [FORCE] [JUSTID]
*
* Gets ownership of one or multiple messages in the Pending Entries List
* of a given stream consumer group.
*
* If the message ID (among the specified ones) exists, and its idle
* time greater or equal to <min-idle-time>, then the message new owner
* becomes the specified <consumer>. If the minimum idle time specified
* is zero, messages are claimed regardless of their idle time.
*
* All the messages that cannot be found inside the pending entires list
* are ignored, but in case the FORCE option is used. In that case we
* create the NACK (representing a not yet acknowledged message) entry in
* the consumer group PEL.
*
* This command creates the consumer as side effect if it does not yet
* exists. Moreover the command reset the idle time of the message to 0,
* even if by using the IDLE or TIME options, the user can control the
* new idle time.
*
* The options at the end can be used in order to specify more attributes
* to set in the representation of the pending message:
*
* 1. IDLE <ms>:
* Set the idle time (last time it was delivered) of the message.
* If IDLE is not specified, an IDLE of 0 is assumed, that is,
* the time count is reset because the message has now a new
* owner trying to process it.
*
* 2. TIME <ms-unix-time>:
* This is the same as IDLE but instead of a relative amount of
* milliseconds, it sets the idle time to a specific unix time
* (in milliseconds). This is useful in order to rewrite the AOF
* file generating XCLAIM commands.
*
* 3. RETRYCOUNT <count>:
* Set the retry counter to the specified value. This counter is
* incremented every time a message is delivered again. Normally
* XCLAIM does not alter this counter, which is just served to clients
* when the XPENDING command is called: this way clients can detect
* anomalies, like messages that are never processed for some reason
* after a big number of delivery attempts.
*
* 4. FORCE:
* Creates the pending message entry in the PEL even if certain
* specified IDs are not already in the PEL assigned to a different
* client. However the message must be exist in the stream, otherwise
* the IDs of non existing messages are ignored.
*
* 5. JUSTID:
* Return just an array of IDs of messages successfully claimed,
* without returning the actual message.
*
* The command returns an array of messages that the user
* successfully claimed, so that the caller is able to understand
* what messages it is now in charge of. */
void xclaimCommand(client *c) {
streamCG *group;
robj *o = lookupKeyRead(c->db,c->argv[1]);
long long minidle; /* Minimum idle time argument. */
long long retrycount = -1; /* -1 means RETRYCOUNT option not given. */
mstime_t deliverytime = -1; /* -1 means IDLE/TIME options not given. */
int force = 0;
int justid = 0;
if (o) {
if (checkType(c,o,OBJ_STREAM)) return; /* Type error. */
group = streamLookupCG(o->ptr,c->argv[2]->ptr);
}
/* No key or group? Send an error given that the group creation
* is mandatory. */
if (o == NULL || group == NULL) {
addReplyErrorFormat(c,"-NOGROUP No such key '%s' or "
"consumer group '%s'", c->argv[1]->ptr,
c->argv[2]->ptr);
return;
}
if (getLongLongFromObjectOrReply(c,c->argv[4],&minidle,
"Invalid min-idle-time argument for XCLAIM")
!= C_OK) return;
if (minidle < 0) minidle = 0;
/* Start parsing the IDs, so that we abort ASAP if there is a syntax
* error: the return value of this command cannot be an error in case
* the client successfully claimed some message, so it should be
* executed in a "all or nothing" fashion. */
int j;
for (j = 4; j < c->argc; j++) {
streamID id;
if (streamParseIDOrReply(NULL,c->argv[j],&id,0) != C_OK) break;
}
int last_id_arg = j-1; /* Next time we iterate the IDs we now the range. */
/* If we stopped because some IDs cannot be parsed, perhaps they
* are trailing options. */
time_t now = mstime();
for (; j < c->argc; j++) {
int moreargs = (c->argc-1) - j; /* Number of additional arguments. */
char *opt = c->argv[j]->ptr;
if (!strcasecmp(opt,"FORCE")) {
force = 1;
} else if (!strcasecmp(opt,"JUSTID")) {
justid = 1;
} else if (!strcasecmp(opt,"IDLE") && moreargs) {
j++;
if (getLongLongFromObjectOrReply(c,c->argv[j],&deliverytime,
"Invalid IDLE option argument for XCLAIM")
!= C_OK) return;
deliverytime = now - deliverytime;
} else if (!strcasecmp(opt,"TIME") && moreargs) {
j++;
if (getLongLongFromObjectOrReply(c,c->argv[j],&deliverytime,
"Invalid IDLE option argument for XCLAIM")
!= C_OK) return;
} else if (!strcasecmp(opt,"RETRYCOUNT") && moreargs) {
j++;
if (getLongLongFromObjectOrReply(c,c->argv[j],&retrycount,
"Invalid IDLE option argument for XCLAIM")
!= C_OK) return;
} else {
addReplyErrorFormat(c,"Unrecognized XCLAIM option '%s'",opt);
return;
}
}
if (deliverytime != -1) {
/* If a delivery time was passed, either with IDLE or TIME, we
* do some sanity check on it, and set the deliverytime to now
* (which is a sane choice usually) if the value is bogus.
* To raise an error here is not wise because clients may compute
* the idle time doing some math startin from their local time,
* and this is not a good excuse to fail in case, for instance,
* the computed time is a bit in the future from our POV. */
if (deliverytime < 0 || deliverytime > now) deliverytime = now;
} else {
/* If no IDLE/TIME option was passed, we want the last delivery
* time to be now, so that the idle time of the message will be
* zero. */
deliverytime = now;
}
/* Do the actual claiming. */
streamConsumer *consumer = streamLookupConsumer(group,c->argv[3]->ptr,1);
void *arraylenptr = addDeferredMultiBulkLength(c);
size_t arraylen = 0;
for (int j = 5; j <= last_id_arg; j++) {
streamID id;
unsigned char buf[sizeof(streamID)];
if (streamParseIDOrReply(c,c->argv[j],&id,0) != C_OK) return;
streamEncodeID(buf,&id);
/* Lookup the ID in the group PEL. */
streamNACK *nack = raxFind(group->pel,buf,sizeof(buf));
/* If FORCE is passed, let's check if at least the entry
* exists in the Stream. In such case, we'll crate a new
* entry in the PEL from scratch, so that XCLAIM can also
* be used to create entries in the PEL. Useful for AOF
* and replication of consumer groups. */
if (force && nack == raxNotFound) {
streamIterator myiterator;
streamIteratorStart(&myiterator,o->ptr,&id,&id,0);
int64_t numfields;
int found = 0;
streamID item_id;
if (streamIteratorGetID(&myiterator,&item_id,&numfields)) found = 1;
streamIteratorStop(&myiterator);
/* Item must exist for us to create a NACK for it. */
if (!found) continue;
/* Create the NACK. */
nack = streamCreateNACK(NULL);
raxInsert(group->pel,buf,sizeof(buf),nack,NULL);
}
if (nack != raxNotFound) {
/* We need to check if the minimum idle time requested
* by the caller is satisfied by this entry. */
if (minidle) {
mstime_t this_idle = now - nack->delivery_time;
if (this_idle < minidle) continue;
}
/* Remove the entry from the old consumer.
* Note that nack->consumer is NULL if we created the
* NACK above because of the FORCE option. */
if (nack->consumer)
raxRemove(nack->consumer->pel,buf,sizeof(buf),NULL);
/* Update the consumer and idle time. */
nack->consumer = consumer;
nack->delivery_time = deliverytime;
/* Set the delivery attempts counter if given. */
if (retrycount >= 0) nack->delivery_count = retrycount;
/* Add the entry in the new cosnumer local PEL. */
raxInsert(consumer->pel,buf,sizeof(buf),nack,NULL);
/* Send the reply for this entry. */
if (justid) {
addReplyStreamID(c,&id);
} else {
streamReplyWithRange(c,o->ptr,&id,NULL,1,0,NULL,NULL,
STREAM_RWR_RAWENTRIES);
}
arraylen++;
}
}
setDeferredMultiBulkLength(c,arraylenptr,arraylen);
}
/* XINFO <key> [CONSUMERS group|GROUPS|STREAM]. STREAM is the default */