X-Git-Url: https://git.saurik.com/redis.git/blobdiff_plain/c4705381422ead4ad99f4b7a3bc11f059c460401..4c8bd905a0751c19279c98d2dbd681a08297e38e:/src/ziplist.c diff --git a/src/ziplist.c b/src/ziplist.c index a6383517..639e4b61 100644 --- a/src/ziplist.c +++ b/src/ziplist.c @@ -67,9 +67,9 @@ #include #include #include "zmalloc.h" +#include "util.h" #include "ziplist.h" - -int ll2string(char *s, size_t len, long long value); +#include "endian.h" #define ZIP_END 255 #define ZIP_BIGLEN 254 @@ -119,6 +119,7 @@ static unsigned int zipEntryEncoding(unsigned char *p) { return p[0] & 0xf0; } assert(NULL); + return 0; } /* Return bytes needed to store integer encoded by 'encoding' */ @@ -129,13 +130,14 @@ static unsigned int zipIntSize(unsigned char encoding) { case ZIP_INT_64B: return sizeof(int64_t); } assert(NULL); + return 0; } /* 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 = zipEntryEncoding(p); - unsigned int len; + unsigned int len = 0; if (ZIP_IS_STR(encoding)) { switch(encoding) { @@ -144,7 +146,7 @@ static unsigned int zipDecodeLength(unsigned char *p, unsigned int *lensize) { if (lensize) *lensize = 1; break; case ZIP_STR_14B: - len = ((p[0] & 0x3f) << 6) | p[1]; + len = ((p[0] & 0x3f) << 8) | p[1]; if (lensize) *lensize = 2; break; case ZIP_STR_32B: @@ -205,6 +207,7 @@ static unsigned int zipPrevDecodeLength(unsigned char *p, unsigned int *lensize) } else { if (lensize) *lensize = 1+sizeof(len); memcpy(&len,p+1,sizeof(len)); + memrev32ifbe(&len); } return len; } @@ -221,11 +224,21 @@ static unsigned int zipPrevEncodeLength(unsigned char *p, unsigned int len) { } else { p[0] = ZIP_BIGLEN; memcpy(p+1,&len,sizeof(len)); + memrev32ifbe(p+1); return 1+sizeof(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)); + memrev32ifbe(p+1); +} + /* 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) { @@ -238,22 +251,9 @@ static int zipPrevLenByteDiff(unsigned char *p, unsigned int len) { * Stores the integer value in 'v' and its encoding in 'encoding'. */ static int zipTryEncoding(unsigned char *entry, unsigned int entrylen, long long *v, unsigned char *encoding) { long long value; - char *eptr; - char buf[32]; if (entrylen >= 32 || entrylen == 0) return 0; - if (entry[0] == '-' || (entry[0] >= '0' && entry[0] <= '9')) { - int slen; - - /* Perform a back-and-forth conversion to make sure that - * the string turned into an integer is not losing any info. */ - memcpy(buf,entry,entrylen); - buf[entrylen] = '\0'; - value = strtoll(buf,&eptr,10); - if (eptr[0] != '\0') return 0; - slen = ll2string(buf,32,value); - if (entrylen != (unsigned)slen || memcmp(buf,entry,slen)) return 0; - + if (string2ll((char*)entry,entrylen,&value)) { /* 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) { @@ -277,12 +277,15 @@ static void zipSaveInteger(unsigned char *p, int64_t value, unsigned char encodi if (encoding == ZIP_INT_16B) { i16 = value; memcpy(p,&i16,sizeof(i16)); + memrev16ifbe(p); } else if (encoding == ZIP_INT_32B) { i32 = value; memcpy(p,&i32,sizeof(i32)); + memrev32ifbe(p); } else if (encoding == ZIP_INT_64B) { i64 = value; memcpy(p,&i64,sizeof(i64)); + memrev64ifbe(p); } else { assert(NULL); } @@ -292,15 +295,18 @@ static void zipSaveInteger(unsigned char *p, int64_t value, unsigned char encodi static int64_t zipLoadInteger(unsigned char *p, unsigned char encoding) { int16_t i16; int32_t i32; - int64_t i64, ret; + int64_t i64, ret = 0; if (encoding == ZIP_INT_16B) { memcpy(&i16,p,sizeof(i16)); + memrev16ifbe(&i16); ret = i16; } else if (encoding == ZIP_INT_32B) { memcpy(&i32,p,sizeof(i32)); + memrev16ifbe(&i32); ret = i32; } else if (encoding == ZIP_INT_64B) { memcpy(&i64,p,sizeof(i64)); + memrev16ifbe(&i64); ret = i64; } else { assert(NULL); @@ -344,11 +350,93 @@ 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) { + size_t curlen = ZIPLIST_BYTES(zl), rawlen, rawlensize; + size_t 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); + p = zl+offset; + + /* Current pointer and offset for next element. */ + np = p+rawlen; + noffset = np-zl; + + /* Update tail offset when next element is not the tail element. */ + if ((zl+ZIPLIST_TAIL_OFFSET(zl)) != np) + ZIPLIST_TAIL_OFFSET(zl) += extra; + + /* Move the tail to the back. */ + memmove(np+rawlensize, + np+next.prevrawlensize, + curlen-noffset-next.prevrawlensize-1); + zipPrevEncodeLength(np,rawlen); + + /* Advance the cursor */ + p += rawlen; + curlen += extra; + } 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; + size_t offset; int nextdiff = 0; - zlentry first = zipEntry(p); + zlentry first, tail; + + first = zipEntry(p); for (i = 0; p[0] != ZIP_END && i < num; i++) { p += zipRawEntryLength(p); deleted++; @@ -365,7 +453,14 @@ 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); @@ -375,29 +470,38 @@ 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; } /* Insert item at "p". */ 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; + size_t curlen = ZIPLIST_BYTES(zl), reqlen, prevlen = 0; + size_t offset; + int nextdiff = 0; unsigned char encoding = 0; - long long value; - zlentry entry; + long long value = 123456789; /* initialized to avoid warning. Using a value + that is easy to see if for some reason + we use it uninitialized. */ + 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); } } @@ -429,15 +533,32 @@ 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); @@ -481,7 +602,12 @@ unsigned char *ziplistIndex(unsigned char *zl, int index) { return (p[0] == ZIP_END || index > 0) ? NULL : p; } -/* Return pointer to next entry in ziplist. */ +/* Return pointer to next entry in ziplist. + * + * zl is the pointer to the ziplist + * p is the pointer to the current element + * + * The element after 'p' is returned, otherwise NULL if we are at the end. */ unsigned char *ziplistNext(unsigned char *zl, unsigned char *p) { ((void) zl); @@ -510,6 +636,7 @@ unsigned char *ziplistPrev(unsigned char *zl, unsigned char *p) { return NULL; } else { entry = zipEntry(p); + assert(entry.prevrawlen > 0); return p-entry.prevrawlen; } } @@ -546,7 +673,7 @@ unsigned char *ziplistInsert(unsigned char *zl, unsigned char *p, unsigned char * Also update *p in place, to be able to iterate over the * ziplist, while deleting entries. */ unsigned char *ziplistDelete(unsigned char *zl, unsigned char **p) { - unsigned int offset = *p-zl; + size_t offset = *p-zl; zl = __ziplistDelete(zl,*p,1); /* Store pointer to current element in p, because ziplistDelete will @@ -608,34 +735,70 @@ unsigned int ziplistLen(unsigned char *zl) { return len; } -/* Return size in bytes of ziplist. */ -unsigned int ziplistSize(unsigned char *zl) { +/* Return ziplist blob size in bytes. */ +size_t ziplistBlobLen(unsigned char *zl) { return ZIPLIST_BYTES(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)p, + index, + (unsigned long) (p-zl), + entry.headersize+entry.len, + entry.headersize, + entry.prevrawlen, + entry.prevrawlensize, + entry.len); p += entry.headersize; if (ZIP_IS_STR(entry.encoding)) { - fwrite(p,entry.len,1,stdout); + if (entry.len > 40) { + if (fwrite(p,40,1,stdout) == 0) perror("fwrite"); + printf("..."); + } else { + if (entry.len && + fwrite(p,entry.len,1,stdout) == 0) perror("fwrite"); + } } else { printf("%lld", (long long) zipLoadInteger(p,entry.encoding)); } printf("\n"); p += entry.len; + index++; } printf("{end}\n\n"); } #ifdef ZIPLIST_TEST_MAIN #include +#include "adlist.h" +#include "sds.h" + +#define debug(f, ...) { if (DEBUG) printf(f, __VA_ARGS__); } unsigned char *createList() { unsigned char *zl = ziplistNew(); @@ -707,7 +870,7 @@ void pop(unsigned char *zl, int where) { printf("Pop tail: "); if (vstr) - fwrite(vstr,vlen,1,stdout); + if (vlen && fwrite(vstr,vlen,1,stdout) == 0) perror("fwrite"); else printf("%lld", vlong); @@ -719,12 +882,41 @@ void pop(unsigned char *zl, int where) { } } +int randstring(char *target, unsigned int min, unsigned int max) { + int p, len = min+rand()%(max-min+1); + int minval, maxval; + switch(rand() % 3) { + case 0: + minval = 0; + maxval = 255; + break; + case 1: + minval = 48; + maxval = 122; + break; + case 2: + minval = 48; + maxval = 52; + break; + default: + assert(NULL); + } + + while(p < len) + target[p++] = minval+rand()%(maxval-minval+1); + return len; +} + int main(int argc, char **argv) { unsigned char *zl, *p; unsigned char *entry; 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); @@ -752,7 +944,7 @@ int main(int argc, char **argv) { return 1; } if (entry) { - fwrite(entry,elen,1,stdout); + if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite"); printf("\n"); } else { printf("%lld\n", value); @@ -782,7 +974,7 @@ int main(int argc, char **argv) { return 1; } if (entry) { - fwrite(entry,elen,1,stdout); + if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite"); printf("\n"); } else { printf("%lld\n", value); @@ -799,7 +991,7 @@ int main(int argc, char **argv) { return 1; } if (entry) { - fwrite(entry,elen,1,stdout); + if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite"); printf("\n"); } else { printf("%lld\n", value); @@ -827,7 +1019,7 @@ int main(int argc, char **argv) { while (ziplistGet(p, &entry, &elen, &value)) { printf("Entry: "); if (entry) { - fwrite(entry,elen,1,stdout); + if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite"); } else { printf("%lld", value); } @@ -844,7 +1036,7 @@ int main(int argc, char **argv) { while (ziplistGet(p, &entry, &elen, &value)) { printf("Entry: "); if (entry) { - fwrite(entry,elen,1,stdout); + if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite"); } else { printf("%lld", value); } @@ -861,7 +1053,7 @@ int main(int argc, char **argv) { while (ziplistGet(p, &entry, &elen, &value)) { printf("Entry: "); if (entry) { - fwrite(entry,elen,1,stdout); + if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite"); } else { printf("%lld", value); } @@ -890,7 +1082,7 @@ int main(int argc, char **argv) { while (ziplistGet(p, &entry, &elen, &value)) { printf("Entry: "); if (entry) { - fwrite(entry,elen,1,stdout); + if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite"); } else { printf("%lld", value); } @@ -907,7 +1099,7 @@ int main(int argc, char **argv) { while (ziplistGet(p, &entry, &elen, &value)) { printf("Entry: "); if (entry) { - fwrite(entry,elen,1,stdout); + if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite"); } else { printf("%lld", value); } @@ -964,7 +1156,8 @@ int main(int argc, char **argv) { } else { printf("Entry: "); if (entry) { - fwrite(entry,elen,1,stdout); + if (elen && fwrite(entry,elen,1,stdout) == 0) + perror("fwrite"); } else { printf("%lld",value); } @@ -976,6 +1169,25 @@ int main(int argc, char **argv) { ziplistRepr(zl); } + printf("Regression test for >255 byte strings:\n"); + { + char v1[257],v2[257]; + memset(v1,'x',256); + memset(v2,'y',256); + zl = ziplistNew(); + zl = ziplistPush(zl,(unsigned char*)v1,strlen(v1),ZIPLIST_TAIL); + zl = ziplistPush(zl,(unsigned char*)v2,strlen(v2),ZIPLIST_TAIL); + + /* Pop values again and compare their value. */ + p = ziplistIndex(zl,0); + assert(ziplistGet(p,&entry,&elen,&value)); + assert(strncmp(v1,(char*)entry,elen) == 0); + p = ziplistIndex(zl,1); + assert(ziplistGet(p,&entry,&elen,&value)); + assert(strncmp(v2,(char*)entry,elen) == 0); + printf("SUCCESS\n\n"); + } + printf("Create long list and check indices:\n"); { zl = ziplistNew(); @@ -1019,7 +1231,84 @@ 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,j,len,where; + unsigned char *p; + char buf[1024]; + int buflen; + list *ref; + listNode *refnode; + + /* Hold temp vars from ziplist */ + unsigned char *sstr; + unsigned int slen; + long long sval; + + for (i = 0; i < 20000; i++) { + zl = ziplistNew(); + ref = listCreate(); + listSetFreeMethod(ref,sdsfree); + len = rand() % 256; + + /* Create lists */ + for (j = 0; j < len; j++) { + where = (rand() & 1) ? ZIPLIST_HEAD : ZIPLIST_TAIL; + if (rand() % 2) { + buflen = randstring(buf,1,sizeof(buf)-1); + } else { + switch(rand() % 3) { + case 0: + buflen = sprintf(buf,"%lld",(0LL + rand()) >> 20); + break; + case 1: + buflen = sprintf(buf,"%lld",(0LL + rand())); + break; + case 2: + buflen = sprintf(buf,"%lld",(0LL + rand()) << 20); + break; + default: + assert(NULL); + } + } + + /* Add to ziplist */ + zl = ziplistPush(zl, (unsigned char*)buf, buflen, where); + + /* Add to reference list */ + if (where == ZIPLIST_HEAD) { + listAddNodeHead(ref,sdsnewlen(buf, buflen)); + } else if (where == ZIPLIST_TAIL) { + listAddNodeTail(ref,sdsnewlen(buf, buflen)); + } else { + assert(NULL); + } + } + + assert(listLength(ref) == ziplistLen(zl)); + for (j = 0; j < len; j++) { + /* Naive way to get elements, but similar to the stresser + * executed from the Tcl test suite. */ + p = ziplistIndex(zl,j); + refnode = listIndex(ref,j); + + assert(ziplistGet(p,&sstr,&slen,&sval)); + if (sstr == NULL) { + buflen = sprintf(buf,"%lld",sval); + } else { + buflen = slen; + memcpy(buf,sstr,buflen); + buf[buflen] = '\0'; + } + assert(memcmp(buf,listNodeValue(refnode),buflen) == 0); + } + zfree(zl); + listRelease(ref); + } + printf("SUCCESS\n\n"); } printf("Stress with variable ziplist size:\n");