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Merge remote branch 'pietern/ziplist-eff'

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antirez 2010-09-22 12:59:25 +02:00
commit 5171777bf1
1 changed files with 356 additions and 96 deletions
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452
src/ziplist.c
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@ -1,17 +1,63 @@
/* Memory layout of a ziplist, containing "foo", "bar", "quux":
* <zlbytes><zllen><len>"foo"<len>"bar"<len>"quux"
/* The ziplist is a specially encoded dually linked list that is designed
* to be very memory efficient. It stores both strings and integer values,
* where integers are encoded as actual integers instead of a series of
* characters. It allows push and pop operations on either side of the list
* in O(1) time. However, because every operation requires a reallocation of
* the memory used by the ziplist, the actual complexity is related to the
* amount of memory used by the ziplist.
*
* <zlbytes> is an unsigned integer to hold the number of bytes that
* the ziplist occupies. This is stored to not have to traverse the ziplist
* to know the new length when pushing.
* ----------------------------------------------------------------------------
*
* <zllen> is the number of items in the ziplist. When this value is
* greater than 254, we need to traverse the entire list to know
* how many items it holds.
* ZIPLIST OVERALL LAYOUT:
* The general layout of the ziplist is as follows:
* <zlbytes><zltail><zllen><entry><entry><zlend>
*
* <len> is the number of bytes occupied by a single entry. When this
* number is greater than 253, the length will occupy 5 bytes, where
* the extra bytes contain an unsigned integer to hold the length.
* <zlbytes> is an unsigned integer to hold the number of bytes that the
* ziplist occupies. This value needs to be stored to be able to resize the
* entire structure without the need to traverse it first.
*
* <zltail> is the offset to the last entry in the list. This allows a pop
* operation on the far side of the list without the need for full traversal.
*
* <zllen> is the number of entries.When this value is larger than 2**16-2,
* we need to traverse the entire list to know how many items it holds.
*
* <zlend> is a single byte special value, equal to 255, which indicates the
* end of the list.
*
* ZIPLIST ENTRIES:
* Every entry in the ziplist is prefixed by a header that contains two pieces
* of information. First, the length of the previous entry is stored to be
* able to traverse the list from back to front. Second, the encoding with an
* optional string length of the entry itself is stored.
*
* The length of the previous entry is encoded in the following way:
* If this length is smaller than 254 bytes, it will only consume a single
* byte that takes the length as value. When the length is greater than or
* equal to 254, it will consume 5 bytes. The first byte is set to 254 to
* indicate a larger value is following. The remaining 4 bytes take the
* length of the previous entry as value.
*
* The other header field of the entry itself depends on the contents of the
* entry. When the entry is a string, the first 2 bits of this header will hold
* the type of encoding used to store the length of the string, followed by the
* actual length of the string. When the entry is an integer the first 2 bits
* are both set to 1. The following 2 bits are used to specify what kind of
* integer will be stored after this header. An overview of the different
* types and encodings is as follows:
*
* |00pppppp| - 1 byte
* String value with length less than or equal to 63 bytes (6 bits).
* |01pppppp|qqqqqqqq| - 2 bytes
* String value with length less than or equal to 16383 bytes (14 bits).
* |10______|qqqqqqqq|rrrrrrrr|ssssssss|tttttttt| - 5 bytes
* String value with length greater than or equal to 16384 bytes.
* |1100____| - 1 byte
* Integer encoded as int16_t (2 bytes).
* |1101____| - 1 byte
* Integer encoded as int32_t (4 bytes).
* |1110____| - 1 byte
* Integer encoded as int64_t (8 bytes).
*/
#include <stdio.h>
@ -25,25 +71,20 @@
int ll2string(char *s, size_t len, long long value);
/* Important note: the ZIP_END value is used to depict the end of the
* ziplist structure. When a pointer contains an entry, the first couple
* of bytes contain the encoded length of the previous entry. This length
* is encoded as ZIP_ENC_RAW length, so the first two bits will contain 00
* and the byte will therefore never have a value of 255. */
#define ZIP_END 255
#define ZIP_BIGLEN 254
/* Entry encoding */
#define ZIP_ENC_RAW 0
#define ZIP_ENC_INT16 1
#define ZIP_ENC_INT32 2
#define ZIP_ENC_INT64 3
#define ZIP_ENCODING(p) ((p)[0] >> 6)
/* Different encoding/length possibilities */
#define ZIP_STR_06B (0 << 6)
#define ZIP_STR_14B (1 << 6)
#define ZIP_STR_32B (2 << 6)
#define ZIP_INT_16B (0xc0 | 0<<4)
#define ZIP_INT_32B (0xc0 | 1<<4)
#define ZIP_INT_64B (0xc0 | 2<<4)
/* Length encoding for raw entries */
#define ZIP_LEN_INLINE 0
#define ZIP_LEN_UINT16 1
#define ZIP_LEN_UINT32 2
/* Macro's to determine type */
#define ZIP_IS_STR(enc) (((enc) & 0xc0) < 0xc0)
#define ZIP_IS_INT(enc) (!ZIP_IS_STR(enc) && ((enc) & 0x30) < 0x30)
/* Utility macros */
#define ZIPLIST_BYTES(zl) (*((uint32_t*)(zl)))
@ -67,14 +108,25 @@ typedef struct zlentry {
unsigned char *p;
} zlentry;
/* Return the encoding pointer to by 'p'. */
static unsigned int zipEntryEncoding(unsigned char *p) {
/* String encoding: 2 MSBs */
unsigned char b = p[0] & 0xc0;
if (b < 0xc0) {
return b;
} else {
/* Integer encoding: 4 MSBs */
return p[0] & 0xf0;
}
assert(NULL);
}
/* Return bytes needed to store integer encoded by 'encoding' */
static unsigned int zipEncodingSize(unsigned char encoding) {
if (encoding == ZIP_ENC_INT16) {
return sizeof(int16_t);
} else if (encoding == ZIP_ENC_INT32) {
return sizeof(int32_t);
} else if (encoding == ZIP_ENC_INT64) {
return sizeof(int64_t);
static unsigned int zipIntSize(unsigned char encoding) {
switch(encoding) {
case ZIP_INT_16B: return sizeof(int16_t);
case ZIP_INT_32B: return sizeof(int32_t);
case ZIP_INT_64B: return sizeof(int64_t);
}
assert(NULL);
}
@ -82,23 +134,28 @@ static unsigned int zipEncodingSize(unsigned char encoding) {
/* Decode the encoded length pointed by 'p'. If a pointer to 'lensize' is
* provided, it is set to the number of bytes required to encode the length. */
static unsigned int zipDecodeLength(unsigned char *p, unsigned int *lensize) {
unsigned char encoding = ZIP_ENCODING(p), lenenc;
unsigned char encoding = zipEntryEncoding(p);
unsigned int len;
if (encoding == ZIP_ENC_RAW) {
lenenc = (p[0] >> 4) & 0x3;
if (lenenc == ZIP_LEN_INLINE) {
len = p[0] & 0xf;
if (ZIP_IS_STR(encoding)) {
switch(encoding) {
case ZIP_STR_06B:
len = p[0] & 0x3f;
if (lensize) *lensize = 1;
} else if (lenenc == ZIP_LEN_UINT16) {
len = p[1] | (p[2] << 8);
if (lensize) *lensize = 3;
} else {
len = p[1] | (p[2] << 8) | (p[3] << 16) | (p[4] << 24);
break;
case ZIP_STR_14B:
len = ((p[0] & 0x3f) << 6) | p[1];
if (lensize) *lensize = 2;
break;
case ZIP_STR_32B:
len = (p[1] << 24) | (p[2] << 16) | (p[3] << 8) | p[4];
if (lensize) *lensize = 5;
break;
default:
assert(NULL);
}
} else {
len = zipEncodingSize(encoding);
len = zipIntSize(encoding);
if (lensize) *lensize = 1;
}
return len;
@ -106,34 +163,36 @@ static unsigned int zipDecodeLength(unsigned char *p, unsigned int *lensize) {
/* Encode the length 'l' writing it in 'p'. If p is NULL it just returns
* the amount of bytes required to encode such a length. */
static unsigned int zipEncodeLength(unsigned char *p, char encoding, unsigned int rawlen) {
unsigned char len = 1, lenenc, buf[5];
if (encoding == ZIP_ENC_RAW) {
if (rawlen <= 0xf) {
static unsigned int zipEncodeLength(unsigned char *p, unsigned char encoding, unsigned int rawlen) {
unsigned char len = 1, buf[5];
if (ZIP_IS_STR(encoding)) {
/* Although encoding is given it may not be set for strings,
* so we determine it here using the raw length. */
if (rawlen <= 0x3f) {
if (!p) return len;
lenenc = ZIP_LEN_INLINE;
buf[0] = rawlen;
} else if (rawlen <= 0xffff) {
len += 2;
buf[0] = ZIP_STR_06B | rawlen;
} else if (rawlen <= 0x3fff) {
len += 1;
if (!p) return len;
lenenc = ZIP_LEN_UINT16;
buf[1] = (rawlen ) & 0xff;
buf[2] = (rawlen >> 8) & 0xff;
buf[0] = ZIP_STR_14B | ((rawlen >> 8) & 0x3f);
buf[1] = rawlen & 0xff;
} else {
len += 4;
if (!p) return len;
lenenc = ZIP_LEN_UINT32;
buf[1] = (rawlen ) & 0xff;
buf[2] = (rawlen >> 8) & 0xff;
buf[3] = (rawlen >> 16) & 0xff;
buf[4] = (rawlen >> 24) & 0xff;
buf[0] = ZIP_STR_32B;
buf[1] = (rawlen >> 24) & 0xff;
buf[2] = (rawlen >> 16) & 0xff;
buf[3] = (rawlen >> 8) & 0xff;
buf[4] = rawlen & 0xff;
}
buf[0] = (lenenc << 4) | (buf[0] & 0xf);
} else {
/* Implies integer encoding, so length is always 1. */
if (!p) return len;
buf[0] = encoding;
}
if (!p) return len;
/* Apparently we need to store the length in 'p' */
buf[0] = (encoding << 6) | (buf[0] & 0x3f);
/* Store this length at p */
memcpy(p,buf,len);
return len;
}
@ -167,6 +226,14 @@ static unsigned int zipPrevEncodeLength(unsigned char *p, unsigned int len) {
}
}
/* Encode the length of the previous entry and write it to "p". This only
* uses the larger encoding (required in __ziplistCascadeUpdate). */
static void zipPrevEncodeLengthForceLarge(unsigned char *p, unsigned int len) {
if (p == NULL) return;
p[0] = ZIP_BIGLEN;
memcpy(p+1,&len,sizeof(len));
}
/* Return the difference in number of bytes needed to store the new length
* "len" on the entry pointed to by "p". */
static int zipPrevLenByteDiff(unsigned char *p, unsigned int len) {
@ -198,11 +265,11 @@ static int zipTryEncoding(unsigned char *entry, unsigned int entrylen, long long
/* Great, the string can be encoded. Check what's the smallest
* of our encoding types that can hold this value. */
if (value >= INT16_MIN && value <= INT16_MAX) {
*encoding = ZIP_ENC_INT16;
*encoding = ZIP_INT_16B;
} else if (value >= INT32_MIN && value <= INT32_MAX) {
*encoding = ZIP_ENC_INT32;
*encoding = ZIP_INT_32B;
} else {
*encoding = ZIP_ENC_INT64;
*encoding = ZIP_INT_64B;
}
*v = value;
return 1;
@ -215,13 +282,13 @@ static void zipSaveInteger(unsigned char *p, int64_t value, unsigned char encodi
int16_t i16;
int32_t i32;
int64_t i64;
if (encoding == ZIP_ENC_INT16) {
if (encoding == ZIP_INT_16B) {
i16 = value;
memcpy(p,&i16,sizeof(i16));
} else if (encoding == ZIP_ENC_INT32) {
} else if (encoding == ZIP_INT_32B) {
i32 = value;
memcpy(p,&i32,sizeof(i32));
} else if (encoding == ZIP_ENC_INT64) {
} else if (encoding == ZIP_INT_64B) {
i64 = value;
memcpy(p,&i64,sizeof(i64));
} else {
@ -234,13 +301,13 @@ static int64_t zipLoadInteger(unsigned char *p, unsigned char encoding) {
int16_t i16;
int32_t i32;
int64_t i64, ret;
if (encoding == ZIP_ENC_INT16) {
if (encoding == ZIP_INT_16B) {
memcpy(&i16,p,sizeof(i16));
ret = i16;
} else if (encoding == ZIP_ENC_INT32) {
} else if (encoding == ZIP_INT_32B) {
memcpy(&i32,p,sizeof(i32));
ret = i32;
} else if (encoding == ZIP_ENC_INT64) {
} else if (encoding == ZIP_INT_64B) {
memcpy(&i64,p,sizeof(i64));
ret = i64;
} else {
@ -255,7 +322,7 @@ static zlentry zipEntry(unsigned char *p) {
e.prevrawlen = zipPrevDecodeLength(p,&e.prevrawlensize);
e.len = zipDecodeLength(p+e.prevrawlensize,&e.lensize);
e.headersize = e.prevrawlensize+e.lensize;
e.encoding = ZIP_ENCODING(p+e.prevrawlensize);
e.encoding = zipEntryEncoding(p+e.prevrawlensize);
e.p = p;
return e;
}
@ -285,11 +352,86 @@ static unsigned char *ziplistResize(unsigned char *zl, unsigned int len) {
return zl;
}
/* When an entry is inserted, we need to set the prevlen field of the next
* entry to equal the length of the inserted entry. It can occur that this
* length cannot be encoded in 1 byte and the next entry needs to be grow
* a bit larger to hold the 5-byte encoded prevlen. This can be done for free,
* because this only happens when an entry is already being inserted (which
* causes a realloc and memmove). However, encoding the prevlen may require
* that this entry is grown as well. This effect may cascade throughout
* the ziplist when there are consecutive entries with a size close to
* ZIP_BIGLEN, so we need to check that the prevlen can be encoded in every
* consecutive entry.
*
* Note that this effect can also happen in reverse, where the bytes required
* to encode the prevlen field can shrink. This effect is deliberately ignored,
* because it can cause a "flapping" effect where a chain prevlen fields is
* first grown and then shrunk again after consecutive inserts. Rather, the
* field is allowed to stay larger than necessary, because a large prevlen
* field implies the ziplist is holding large entries anyway.
*
* The pointer "p" points to the first entry that does NOT need to be
* updated, i.e. consecutive fields MAY need an update. */
static unsigned char *__ziplistCascadeUpdate(unsigned char *zl, unsigned char *p) {
unsigned int curlen = ZIPLIST_BYTES(zl), rawlen, rawlensize;
unsigned int offset, noffset, extra;
unsigned char *np;
zlentry cur, next;
while (p[0] != ZIP_END) {
cur = zipEntry(p);
rawlen = cur.headersize + cur.len;
rawlensize = zipPrevEncodeLength(NULL,rawlen);
/* Abort if there is no next entry. */
if (p[rawlen] == ZIP_END) break;
next = zipEntry(p+rawlen);
/* Abort when "prevlen" has not changed. */
if (next.prevrawlen == rawlen) break;
if (next.prevrawlensize < rawlensize) {
/* The "prevlen" field of "next" needs more bytes to hold
* the raw length of "cur". */
offset = p-zl;
extra = rawlensize-next.prevrawlensize;
zl = ziplistResize(zl,curlen+extra);
ZIPLIST_TAIL_OFFSET(zl) += extra;
p = zl+offset;
/* Move the tail to the back. */
np = p+rawlen;
noffset = np-zl;
memmove(np+rawlensize,
np+next.prevrawlensize,
curlen-noffset-next.prevrawlensize-1);
zipPrevEncodeLength(np,rawlen);
/* Advance the cursor */
p += rawlen;
} else {
if (next.prevrawlensize > rawlensize) {
/* This would result in shrinking, which we want to avoid.
* So, set "rawlen" in the available bytes. */
zipPrevEncodeLengthForceLarge(p+rawlen,rawlen);
} else {
zipPrevEncodeLength(p+rawlen,rawlen);
}
/* Stop here, as the raw length of "next" has not changed. */
break;
}
}
return zl;
}
/* Delete "num" entries, starting at "p". Returns pointer to the ziplist. */
static unsigned char *__ziplistDelete(unsigned char *zl, unsigned char *p, unsigned int num) {
unsigned int i, totlen, deleted = 0;
int nextdiff = 0;
zlentry first = zipEntry(p);
int offset, nextdiff = 0;
zlentry first, tail;
first = zipEntry(p);
for (i = 0; p[0] != ZIP_END && i < num; i++) {
p += zipRawEntryLength(p);
deleted++;
@ -306,7 +448,14 @@ static unsigned char *__ziplistDelete(unsigned char *zl, unsigned char *p, unsig
zipPrevEncodeLength(p-nextdiff,first.prevrawlen);
/* Update offset for tail */
ZIPLIST_TAIL_OFFSET(zl) -= totlen+nextdiff;
ZIPLIST_TAIL_OFFSET(zl) -= totlen;
/* When the tail contains more than one entry, we need to take
* "nextdiff" in account as well. Otherwise, a change in the
* size of prevlen doesn't have an effect on the *tail* offset. */
tail = zipEntry(p);
if (p[tail.headersize+tail.len] != ZIP_END)
ZIPLIST_TAIL_OFFSET(zl) += nextdiff;
/* Move tail to the front of the ziplist */
memmove(first.p,p-nextdiff,ZIPLIST_BYTES(zl)-(p-zl)-1+nextdiff);
@ -316,8 +465,15 @@ static unsigned char *__ziplistDelete(unsigned char *zl, unsigned char *p, unsig
}
/* Resize and update length */
offset = first.p-zl;
zl = ziplistResize(zl, ZIPLIST_BYTES(zl)-totlen+nextdiff);
ZIPLIST_INCR_LENGTH(zl,-deleted);
p = zl+offset;
/* When nextdiff != 0, the raw length of the next entry has changed, so
* we need to cascade the update throughout the ziplist */
if (nextdiff != 0)
zl = __ziplistCascadeUpdate(zl,p);
}
return zl;
}
@ -326,29 +482,30 @@ static unsigned char *__ziplistDelete(unsigned char *zl, unsigned char *p, unsig
static unsigned char *__ziplistInsert(unsigned char *zl, unsigned char *p, unsigned char *s, unsigned int slen) {
unsigned int curlen = ZIPLIST_BYTES(zl), reqlen, prevlen = 0;
unsigned int offset, nextdiff = 0;
unsigned char *tail;
unsigned char encoding = ZIP_ENC_RAW;
unsigned char encoding = 0;
long long value;
zlentry entry;
zlentry entry, tail;
/* Find out prevlen for the entry that is inserted. */
if (p[0] != ZIP_END) {
entry = zipEntry(p);
prevlen = entry.prevrawlen;
} else {
tail = ZIPLIST_ENTRY_TAIL(zl);
if (tail[0] != ZIP_END) {
prevlen = zipRawEntryLength(tail);
unsigned char *ptail = ZIPLIST_ENTRY_TAIL(zl);
if (ptail[0] != ZIP_END) {
prevlen = zipRawEntryLength(ptail);
}
}
/* See if the entry can be encoded */
if (zipTryEncoding(s,slen,&value,&encoding)) {
reqlen = zipEncodingSize(encoding);
/* 'encoding' is set to the appropriate integer encoding */
reqlen = zipIntSize(encoding);
} else {
/* 'encoding' is untouched, however zipEncodeLength will use the
* string length to figure out how to encode it. */
reqlen = slen;
}
/* We need space for both the length of the previous entry and
* the length of the payload. */
reqlen += zipPrevEncodeLength(NULL,prevlen);
@ -368,22 +525,39 @@ static unsigned char *__ziplistInsert(unsigned char *zl, unsigned char *p, unsig
if (p[0] != ZIP_END) {
/* Subtract one because of the ZIP_END bytes */
memmove(p+reqlen,p-nextdiff,curlen-offset-1+nextdiff);
/* Encode this entry's raw length in the next entry. */
zipPrevEncodeLength(p+reqlen,reqlen);
/* Update offset for tail */
ZIPLIST_TAIL_OFFSET(zl) += reqlen+nextdiff;
ZIPLIST_TAIL_OFFSET(zl) += reqlen;
/* When the tail contains more than one entry, we need to take
* "nextdiff" in account as well. Otherwise, a change in the
* size of prevlen doesn't have an effect on the *tail* offset. */
tail = zipEntry(p+reqlen);
if (p[reqlen+tail.headersize+tail.len] != ZIP_END)
ZIPLIST_TAIL_OFFSET(zl) += nextdiff;
} else {
/* This element will be the new tail. */
ZIPLIST_TAIL_OFFSET(zl) = p-zl;
}
/* When nextdiff != 0, the raw length of the next entry has changed, so
* we need to cascade the update throughout the ziplist */
if (nextdiff != 0) {
offset = p-zl;
zl = __ziplistCascadeUpdate(zl,p+reqlen);
p = zl+offset;
}
/* Write the entry */
p += zipPrevEncodeLength(p,prevlen);
p += zipEncodeLength(p,encoding,slen);
if (encoding != ZIP_ENC_RAW) {
zipSaveInteger(p,value,encoding);
} else {
if (ZIP_IS_STR(encoding)) {
memcpy(p,s,slen);
} else {
zipSaveInteger(p,value,encoding);
}
ZIPLIST_INCR_LENGTH(zl,1);
return zl;
@ -449,6 +623,7 @@ unsigned char *ziplistPrev(unsigned char *zl, unsigned char *p) {
return NULL;
} else {
entry = zipEntry(p);
assert(entry.prevrawlen > 0);
return p-entry.prevrawlen;
}
}
@ -463,7 +638,7 @@ unsigned int ziplistGet(unsigned char *p, unsigned char **sstr, unsigned int *sl
if (sstr) *sstr = NULL;
entry = zipEntry(p);
if (entry.encoding == ZIP_ENC_RAW) {
if (ZIP_IS_STR(entry.encoding)) {
if (sstr) {
*slen = entry.len;
*sstr = p+entry.headersize;
@ -510,7 +685,7 @@ unsigned int ziplistCompare(unsigned char *p, unsigned char *sstr, unsigned int
if (p[0] == ZIP_END) return 0;
entry = zipEntry(p);
if (entry.encoding == ZIP_ENC_RAW) {
if (ZIP_IS_STR(entry.encoding)) {
/* Raw compare */
if (entry.len == slen) {
return memcmp(p+entry.headersize,sstr,slen) == 0;
@ -554,21 +729,52 @@ unsigned int ziplistSize(unsigned char *zl) {
void ziplistRepr(unsigned char *zl) {
unsigned char *p;
int index = 0;
zlentry entry;
printf("{total bytes %d} {length %u}\n",ZIPLIST_BYTES(zl), ZIPLIST_LENGTH(zl));
printf(
"{total bytes %d} "
"{length %u}\n"
"{tail offset %u}\n",
ZIPLIST_BYTES(zl),
ZIPLIST_LENGTH(zl),
ZIPLIST_TAIL_OFFSET(zl));
p = ZIPLIST_ENTRY_HEAD(zl);
while(*p != ZIP_END) {
entry = zipEntry(p);
printf("{offset %ld, header %u, payload %u} ",p-zl,entry.headersize,entry.len);
printf(
"{"
"addr 0x%08lx, "
"index %2d, "
"offset %5ld, "
"rl: %5u, "
"hs %2u, "
"pl: %5u, "
"pls: %2u, "
"payload %5u"
"} ",
(long unsigned int)p,
index,
p-zl,
entry.headersize+entry.len,
entry.headersize,
entry.prevrawlen,
entry.prevrawlensize,
entry.len);
p += entry.headersize;
if (entry.encoding == ZIP_ENC_RAW) {
fwrite(p,entry.len,1,stdout);
if (ZIP_IS_STR(entry.encoding)) {
if (entry.len > 40) {
fwrite(p,40,1,stdout);
printf("...");
} else {
fwrite(p,entry.len,1,stdout);
}
} else {
printf("%lld", (long long) zipLoadInteger(p,entry.encoding));
}
printf("\n");
p += entry.len;
index++;
}
printf("{end}\n\n");
}
@ -664,6 +870,10 @@ int main(int argc, char **argv) {
unsigned int elen;
long long value;
/* If an argument is given, use it as the random seed. */
if (argc == 2)
srand(atoi(argv[1]));
zl = createIntList();
ziplistRepr(zl);
@ -958,7 +1168,57 @@ int main(int argc, char **argv) {
printf("ERROR: \"1025\"\n");
return 1;
}
printf("SUCCESS\n");
printf("SUCCESS\n\n");
}
printf("Stress with random payloads of different encoding:\n");
{
int i, idx, where, len;
long long v;
unsigned char *p;
char buf[0x4041]; /* max length of generated string */
zl = ziplistNew();
for (i = 0; i < 100000; i++) {
where = (rand() & 1) ? ZIPLIST_HEAD : ZIPLIST_TAIL;
if (rand() & 1) {
/* equally likely create a 16, 32 or 64 bit int */
v = (rand() & INT16_MAX) + ((1ll << 32) >> ((rand() % 3)*16));
v *= 2*(rand() & 1)-1; /* randomly flip sign */
sprintf(buf, "%lld", v);
zl = ziplistPush(zl, (unsigned char*)buf, strlen(buf), where);
} else {
/* equally likely generate 6, 14 or >14 bit length */
v = rand() & 0x3f;
v += 0x4000 >> ((rand() % 3)*8);
memset(buf, 'x', v);
zl = ziplistPush(zl, (unsigned char*)buf, v, where);
}
/* delete a random element */
if ((len = ziplistLen(zl)) >= 10) {
idx = rand() % len;
// printf("Delete index %d\n", idx);
// ziplistRepr(zl);
ziplistDeleteRange(zl, idx, 1);
// ziplistRepr(zl);
len--;
}
/* iterate from front to back */
idx = 0;
p = ziplistIndex(zl, 0);
while((p = ziplistNext(zl,p)))
idx++;
assert(len == idx+1);
/* iterate from back to front */
idx = 0;
p = ziplistIndex(zl, -1);
while((p = ziplistPrev(zl,p)))
idx++;
assert(len == idx+1);
}
printf("SUCCESS\n\n");
}
printf("Stress with variable ziplist size:\n");