/*
* 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.
*/
/* TODO:
* - After loading a stream, populate the last ID.
*/
#include "server.h"
#include "endianconv.h"
#include "stream.h"
#define STREAM_BYTES_PER_LISTPACK 4096
/* -----------------------------------------------------------------------
* 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;
return s;
}
/* Free a stream, including the listpacks stored inside the radix tree. */
void freeStream(stream *s) {
raxFreeWithCallback(s->rax,(void(*)(void*))lpFree);
}
/* 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 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. */
int retval = string2ll((char*)e,v,&v);
serverAssert(retval != 0);
return v;
}
/* 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]);
}
/* 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. */
void streamAppendItem(stream *s, robj **argv, int numfields, streamID *added_id) {
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;
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.*/
uint64_t entry_id[2]; /* Entry ID of the new item as 128 bit string. */
streamEncodeID(entry_id,&id);
/* Create a new listpack and radix tree node if needed. */
if (lp == NULL || lp_bytes > STREAM_BYTES_PER_LISTPACK) {
lp = lpNew();
rax_key[0] = entry_id[0];
rax_key[1] = entry_id[1];
raxInsert(s->rax,(unsigned char*)&rax_key,sizeof(rax_key),lp,NULL);
} else {
serverAssert(ri.key_len == sizeof(rax_key));
memcpy(rax_key,ri.key,sizeof(rax_key));
}
/* Populate the listpack with the new entry. We use the following
* encoding:
*
* +--------+----------+-------+-------+-/-+-------+-------+
* |entry-id|num-fields|field-1|value-1|...|field-N|value-N|
* +--------+----------+-------+-------+-/-+-------+-------+
*/
lp = lpAppend(lp,(unsigned char*)entry_id,sizeof(entry_id));
lp = lpAppendInteger(lp,numfields);
for (int i = 0; i < numfields; i++) {
sds field = argv[i*2]->ptr, value = argv[i*2+1]->ptr;
lp = lpAppend(lp,(unsigned char*)field,sdslen(field));
lp = lpAppend(lp,(unsigned char*)value,sdslen(value));
}
/* 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;
}
/* 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. */
size_t streamReplyWithRange(client *c, stream *s, streamID *start, streamID *end, size_t count) {
void *arraylen_ptr = addDeferredMultiBulkLength(c);
size_t arraylen = 0;
/* Seek the radix tree node that contains our start item. */
uint64_t key[2];
uint64_t end_key[2];
streamEncodeID(key,start);
if (end) streamEncodeID(end_key,end);
raxIterator ri;
raxStart(&ri,s->rax);
/* Seek the correct node in the radix tree. */
if (start->ms || start->seq) {
raxSeek(&ri,"<=",(unsigned char*)key,sizeof(key));
if (raxEOF(&ri)) raxSeek(&ri,">",(unsigned char*)key,sizeof(key));
} else {
raxSeek(&ri,"^",NULL,0);
}
/* For every radix tree node, iterate the corresponding listpack,
* returning elmeents when they are within range. */
while (raxNext(&ri)) {
serverAssert(ri.key_len == sizeof(key));
unsigned char *lp = ri.data;
unsigned char *lp_ele = lpFirst(lp);
while(lp_ele) {
int64_t e_len;
unsigned char buf[LP_INTBUF_SIZE];
unsigned char *e = lpGet(lp_ele,&e_len,buf);
serverAssert(e_len == sizeof(streamID));
/* Seek next field: number of elements. */
lp_ele = lpNext(lp,lp_ele);
if (memcmp(e,key,sizeof(key)) >= 0) { /* If current >= start */
if (end && memcmp(e,end_key,sizeof(key)) > 0) {
break; /* We are already out of range. */
}
streamID thisid;
streamDecodeID(e,&thisid);
sds replyid = sdscatfmt(sdsempty(),"+%U.%U\r\n",
thisid.ms,thisid.seq);
/* Emit this stream entry in the client output. */
addReplyMultiBulkLen(c,2);
addReplySds(c,replyid);
int64_t numfields = lpGetInteger(lp_ele);
lp_ele = lpNext(lp,lp_ele);
addReplyMultiBulkLen(c,numfields*2);
for (int64_t i = 0; i < numfields; i++) {
/* Emit two items (key-value) per iteration. */
for (int k = 0; k < 2; k++) {
e = lpGet(lp_ele,&e_len,buf);
addReplyBulkCBuffer(c,e,e_len);
lp_ele = lpNext(lp,lp_ele);
}
}
arraylen++;
if (count && count == arraylen) break;
} else {
/* If we do not emit, we have to discard. */
int64_t numfields = lpGetInteger(lp_ele);
lp_ele = lpNext(lp,lp_ele);
for (int64_t i = 0; i < numfields*2; i++)
lp_ele = lpNext(lp,lp_ele);
}
}
if (count && count == arraylen) break;
}
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. */
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';
uint64_t 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:
addReplyError(c,"Invalid stream ID specified as stream command argument");
return C_ERR;
}
/* XADD key [field value] [field value] ... */
void xaddCommand(client *c) {
if ((c->argc % 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. */
streamID id;
streamAppendItem(s,c->argv+2,(c->argc-2)/2,&id);
sds reply = sdscatfmt(sdsempty(),"+%U.%U\r\n",id.ms,id.seq);
addReplySds(c,reply);
signalModifiedKey(c->db,c->argv[1]);
notifyKeyspaceEvent(NOTIFY_HASH,"xadd",c->argv[1],c->db->id);
server.dirty++;
}
/* XRANGE key start end [COUNT <n>] */
void xrangeCommand(client *c) {
robj *o;
stream *s;
streamID startid, endid;
long long count = 0;
if (streamParseIDOrReply(c,c->argv[2],&startid,0) == C_ERR) return;
if (streamParseIDOrReply(c,c->argv[3],&endid,UINT64_MAX) == C_ERR) return;
/* Parse the COUNT option if any. */
if (c->argc > 4) {
if (strcasecmp(c->argv[4]->ptr,"COUNT") == 0) {
if (getLongLongFromObjectOrReply(c,c->argv[5],&count,NULL) != C_OK)
return;
if (count < 0) count = 0;
} 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);
}
/* 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>] [GROUP <groupname> <ttl>]
* [RETRY <milliseconds> <ttl>] STREAMS key_1 key_2 ... key_N
* ID_1 ID_2 ... ID_N */
void xreadCommand(client *c) {
long long timeout = 0;
long long count = 0;
int streams_count = 0;
int streams_arg = 0;
#define STREAMID_STATIC_VECTOR_LEN 8
streamID static_ids[STREAMID_STATIC_VECTOR_LEN];
streamID *ids = static_ids;
/* Parse arguments. */
for (int i = 1; i < c->argc; i++) {
int moreargs = i != c->argc-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 {
addReply(c,shared.syntaxerr);
return;
}
}
/* STREAMS option is mandatory. */
if (streams_arg == 0) {
addReply(c,shared.syntaxerr);
return;
}
/* Parse the IDs. */
if (streams_count > STREAMID_STATIC_VECTOR_LEN)
ids = zmalloc(sizeof(streamID)*streams_count);
for (int i = streams_arg + streams_count; i < c->argc; i++) {
/* Specifying "$" as last-known-id means that the client wants to be
* served with just the messages that will arrive into the stream
* starting from now. */
if (strcmp(c->argv[i]->ptr,"$") == 0) {
robj *o = lookupKeyRead(c->db,c->argv[i-streams_count]);
int id_idx = i - streams_arg - streams_count;
if (o) {
stream *s = o->ptr;
ids[id_idx] = s->last_id;
} else {
ids[id_idx].ms = 0;
ids[id_idx].seq = 0;
}
continue;
}
if (streamParseIDOrReply(c,c->argv[i],ids+i,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++; /* Can't overflow, it's an uint64_t */
/* 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]);
streamReplyWithRange(c,s,&start,NULL,count);
}
}
/* 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) {
/* 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);
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);
}