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redis/src/object.c

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/* Redis Object implementation.
*
* Copyright (c) 2009-2012, 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 <math.h>
#include <ctype.h>
#ifdef __CYGWIN__
#define strtold(a,b) ((long double)strtod((a),(b)))
#endif
robj *createObject(int type, void *ptr) {
robj *o = zmalloc(sizeof(*o));
o->type = type;
o->encoding = REDIS_ENCODING_RAW;
o->ptr = ptr;
o->refcount = 1;
/* Set the LRU to the current lruclock (minutes resolution). */
o->lru = LRU_CLOCK();
return o;
}
/* Create a string object with encoding REDIS_ENCODING_RAW, that is a plain
* string object where o->ptr points to a proper sds string. */
robj *createRawStringObject(const char *ptr, size_t len) {
return createObject(REDIS_STRING,sdsnewlen(ptr,len));
}
/* Create a string object with encoding REDIS_ENCODING_EMBSTR, that is
* an object where the sds string is actually an unmodifiable string
* allocated in the same chunk as the object itself. */
robj *createEmbeddedStringObject(const char *ptr, size_t len) {
robj *o = zmalloc(sizeof(robj)+sizeof(struct sdshdr8)+len+1);
struct sdshdr8 *sh = (void*)(o+1);
o->type = REDIS_STRING;
o->encoding = REDIS_ENCODING_EMBSTR;
o->ptr = sh+1;
o->refcount = 1;
o->lru = LRU_CLOCK();
sh->len = len;
sh->alloc = len;
sh->flags = SDS_TYPE_8;
if (ptr) {
memcpy(sh->buf,ptr,len);
sh->buf[len] = '\0';
} else {
memset(sh->buf,0,len+1);
}
return o;
}
/* Create a string object with EMBSTR encoding if it is smaller than
* REIDS_ENCODING_EMBSTR_SIZE_LIMIT, otherwise the RAW encoding is
* used.
*
* The current limit of 39 is chosen so that the biggest string object
* we allocate as EMBSTR will still fit into the 64 byte arena of jemalloc. */
#define REDIS_ENCODING_EMBSTR_SIZE_LIMIT 44
robj *createStringObject(const char *ptr, size_t len) {
if (len <= REDIS_ENCODING_EMBSTR_SIZE_LIMIT)
return createEmbeddedStringObject(ptr,len);
else
return createRawStringObject(ptr,len);
}
robj *createStringObjectFromLongLong(long long value) {
robj *o;
if (value >= 0 && value < REDIS_SHARED_INTEGERS) {
incrRefCount(shared.integers[value]);
o = shared.integers[value];
} else {
if (value >= LONG_MIN && value <= LONG_MAX) {
o = createObject(REDIS_STRING, NULL);
o->encoding = REDIS_ENCODING_INT;
o->ptr = (void*)((long)value);
} else {
o = createObject(REDIS_STRING,sdsfromlonglong(value));
}
}
return o;
}
/* Create a string object from a long double. If humanfriendly is non-zero
* it does not use exponential format and trims trailing zeroes at the end,
* however this results in loss of precision. Otherwise exp format is used
* and the output of snprintf() is not modified.
*
* The 'humanfriendly' option is used for INCRBYFLOAT and HINCRBYFLOAT. */
robj *createStringObjectFromLongDouble(long double value, int humanfriendly) {
char buf[256];
int len;
if (isinf(value)) {
/* Libc in odd systems (Hi Solaris!) will format infinite in a
* different way, so better to handle it in an explicit way. */
if (value > 0) {
memcpy(buf,"inf",3);
len = 3;
} else {
memcpy(buf,"-inf",4);
len = 4;
}
} else if (humanfriendly) {
/* We use 17 digits precision since with 128 bit floats that precision
* after rounding is able to represent most small decimal numbers in a
* way that is "non surprising" for the user (that is, most small
* decimal numbers will be represented in a way that when converted
* back into a string are exactly the same as what the user typed.) */
len = snprintf(buf,sizeof(buf),"%.17Lf", value);
/* Now remove trailing zeroes after the '.' */
if (strchr(buf,'.') != NULL) {
char *p = buf+len-1;
while(*p == '0') {
p--;
len--;
}
if (*p == '.') len--;
}
} else {
len = snprintf(buf,sizeof(buf),"%.17Lg", value);
}
return createStringObject(buf,len);
}
/* Duplicate a string object, with the guarantee that the returned object
* has the same encoding as the original one.
*
* This function also guarantees that duplicating a small integere object
* (or a string object that contains a representation of a small integer)
* will always result in a fresh object that is unshared (refcount == 1).
*
* The resulting object always has refcount set to 1. */
robj *dupStringObject(robj *o) {
robj *d;
redisAssert(o->type == REDIS_STRING);
switch(o->encoding) {
case REDIS_ENCODING_RAW:
return createRawStringObject(o->ptr,sdslen(o->ptr));
case REDIS_ENCODING_EMBSTR:
return createEmbeddedStringObject(o->ptr,sdslen(o->ptr));
case REDIS_ENCODING_INT:
d = createObject(REDIS_STRING, NULL);
d->encoding = REDIS_ENCODING_INT;
d->ptr = o->ptr;
return d;
default:
redisPanic("Wrong encoding.");
break;
}
}
robj *createQuicklistObject(void) {
quicklist *l = quicklistCreate();
robj *o = createObject(REDIS_LIST,l);
o->encoding = REDIS_ENCODING_QUICKLIST;
return o;
}
robj *createZiplistObject(void) {
unsigned char *zl = ziplistNew();
robj *o = createObject(REDIS_LIST,zl);
o->encoding = REDIS_ENCODING_ZIPLIST;
return o;
}
robj *createSetObject(void) {
dict *d = dictCreate(&setDictType,NULL);
robj *o = createObject(REDIS_SET,d);
o->encoding = REDIS_ENCODING_HT;
return o;
}
robj *createIntsetObject(void) {
intset *is = intsetNew();
robj *o = createObject(REDIS_SET,is);
o->encoding = REDIS_ENCODING_INTSET;
return o;
}
robj *createHashObject(void) {
unsigned char *zl = ziplistNew();
robj *o = createObject(REDIS_HASH, zl);
o->encoding = REDIS_ENCODING_ZIPLIST;
return o;
}
robj *createZsetObject(void) {
zset *zs = zmalloc(sizeof(*zs));
robj *o;
zs->dict = dictCreate(&zsetDictType,NULL);
zs->zsl = zslCreate();
o = createObject(REDIS_ZSET,zs);
o->encoding = REDIS_ENCODING_SKIPLIST;
return o;
}
robj *createZsetZiplistObject(void) {
unsigned char *zl = ziplistNew();
robj *o = createObject(REDIS_ZSET,zl);
o->encoding = REDIS_ENCODING_ZIPLIST;
return o;
}
void freeStringObject(robj *o) {
if (o->encoding == REDIS_ENCODING_RAW) {
sdsfree(o->ptr);
}
}
void freeListObject(robj *o) {
switch (o->encoding) {
case REDIS_ENCODING_QUICKLIST:
quicklistRelease(o->ptr);
break;
default:
redisPanic("Unknown list encoding type");
}
}
void freeSetObject(robj *o) {
switch (o->encoding) {
case REDIS_ENCODING_HT:
dictRelease((dict*) o->ptr);
break;
case REDIS_ENCODING_INTSET:
zfree(o->ptr);
break;
default:
redisPanic("Unknown set encoding type");
}
}
void freeZsetObject(robj *o) {
zset *zs;
switch (o->encoding) {
case REDIS_ENCODING_SKIPLIST:
zs = o->ptr;
dictRelease(zs->dict);
zslFree(zs->zsl);
zfree(zs);
break;
case REDIS_ENCODING_ZIPLIST:
zfree(o->ptr);
break;
default:
redisPanic("Unknown sorted set encoding");
}
}
void freeHashObject(robj *o) {
switch (o->encoding) {
case REDIS_ENCODING_HT:
dictRelease((dict*) o->ptr);
break;
case REDIS_ENCODING_ZIPLIST:
zfree(o->ptr);
break;
default:
redisPanic("Unknown hash encoding type");
break;
}
}
void incrRefCount(robj *o) {
o->refcount++;
}
void decrRefCount(robj *o) {
if (o->refcount <= 0) redisPanic("decrRefCount against refcount <= 0");
if (o->refcount == 1) {
switch(o->type) {
case REDIS_STRING: freeStringObject(o); break;
case REDIS_LIST: freeListObject(o); break;
case REDIS_SET: freeSetObject(o); break;
case REDIS_ZSET: freeZsetObject(o); break;
case REDIS_HASH: freeHashObject(o); break;
default: redisPanic("Unknown object type"); break;
}
zfree(o);
} else {
o->refcount--;
}
}
/* This variant of decrRefCount() gets its argument as void, and is useful
* as free method in data structures that expect a 'void free_object(void*)'
* prototype for the free method. */
void decrRefCountVoid(void *o) {
decrRefCount(o);
}
/* This function set the ref count to zero without freeing the object.
* It is useful in order to pass a new object to functions incrementing
* the ref count of the received object. Example:
*
* functionThatWillIncrementRefCount(resetRefCount(CreateObject(...)));
*
* Otherwise you need to resort to the less elegant pattern:
*
* *obj = createObject(...);
* functionThatWillIncrementRefCount(obj);
* decrRefCount(obj);
*/
robj *resetRefCount(robj *obj) {
obj->refcount = 0;
return obj;
}
int checkType(redisClient *c, robj *o, int type) {
if (o->type != type) {
addReply(c,shared.wrongtypeerr);
return 1;
}
return 0;
}
int isObjectRepresentableAsLongLong(robj *o, long long *llval) {
redisAssertWithInfo(NULL,o,o->type == REDIS_STRING);
if (o->encoding == REDIS_ENCODING_INT) {
if (llval) *llval = (long) o->ptr;
return REDIS_OK;
} else {
return string2ll(o->ptr,sdslen(o->ptr),llval) ? REDIS_OK : REDIS_ERR;
}
}
/* Try to encode a string object in order to save space */
robj *tryObjectEncoding(robj *o) {
long value;
sds s = o->ptr;
size_t len;
/* Make sure this is a string object, the only type we encode
* in this function. Other types use encoded memory efficient
* representations but are handled by the commands implementing
* the type. */
redisAssertWithInfo(NULL,o,o->type == REDIS_STRING);
/* We try some specialized encoding only for objects that are
* RAW or EMBSTR encoded, in other words objects that are still
* in represented by an actually array of chars. */
if (!sdsEncodedObject(o)) return o;
/* It's not safe to encode shared objects: shared objects can be shared
* everywhere in the "object space" of Redis and may end in places where
* they are not handled. We handle them only as values in the keyspace. */
if (o->refcount > 1) return o;
/* Check if we can represent this string as a long integer.
* Note that we are sure that a string larger than 21 chars is not
* representable as a 32 nor 64 bit integer. */
len = sdslen(s);
if (len <= 21 && string2l(s,len,&value)) {
/* This object is encodable as a long. Try to use a shared object.
* Note that we avoid using shared integers when maxmemory is used
* because every object needs to have a private LRU field for the LRU
* algorithm to work well. */
if ((server.maxmemory == 0 ||
(server.maxmemory_policy != REDIS_MAXMEMORY_VOLATILE_LRU &&
server.maxmemory_policy != REDIS_MAXMEMORY_ALLKEYS_LRU)) &&
value >= 0 &&
value < REDIS_SHARED_INTEGERS)
{
decrRefCount(o);
incrRefCount(shared.integers[value]);
return shared.integers[value];
} else {
if (o->encoding == REDIS_ENCODING_RAW) sdsfree(o->ptr);
o->encoding = REDIS_ENCODING_INT;
o->ptr = (void*) value;
return o;
}
}
/* If the string is small and is still RAW encoded,
* try the EMBSTR encoding which is more efficient.
* In this representation the object and the SDS string are allocated
* in the same chunk of memory to save space and cache misses. */
if (len <= REDIS_ENCODING_EMBSTR_SIZE_LIMIT) {
robj *emb;
if (o->encoding == REDIS_ENCODING_EMBSTR) return o;
emb = createEmbeddedStringObject(s,sdslen(s));
decrRefCount(o);
return emb;
}
/* We can't encode the object...
*
* Do the last try, and at least optimize the SDS string inside
* the string object to require little space, in case there
* is more than 10% of free space at the end of the SDS string.
*
* We do that only for relatively large strings as this branch
* is only entered if the length of the string is greater than
* REDIS_ENCODING_EMBSTR_SIZE_LIMIT. */
if (o->encoding == REDIS_ENCODING_RAW &&
sdsavail(s) > len/10)
{
o->ptr = sdsRemoveFreeSpace(o->ptr);
}
/* Return the original object. */
return o;
}
/* Get a decoded version of an encoded object (returned as a new object).
* If the object is already raw-encoded just increment the ref count. */
robj *getDecodedObject(robj *o) {
robj *dec;
if (sdsEncodedObject(o)) {
incrRefCount(o);
return o;
}
if (o->type == REDIS_STRING && o->encoding == REDIS_ENCODING_INT) {
char buf[32];
ll2string(buf,32,(long)o->ptr);
dec = createStringObject(buf,strlen(buf));
return dec;
} else {
redisPanic("Unknown encoding type");
}
}
/* Compare two string objects via strcmp() or strcoll() depending on flags.
* Note that the objects may be integer-encoded. In such a case we
* use ll2string() to get a string representation of the numbers on the stack
* and compare the strings, it's much faster than calling getDecodedObject().
*
* Important note: when REDIS_COMPARE_BINARY is used a binary-safe comparison
* is used. */
#define REDIS_COMPARE_BINARY (1<<0)
#define REDIS_COMPARE_COLL (1<<1)
int compareStringObjectsWithFlags(robj *a, robj *b, int flags) {
redisAssertWithInfo(NULL,a,a->type == REDIS_STRING && b->type == REDIS_STRING);
char bufa[128], bufb[128], *astr, *bstr;
size_t alen, blen, minlen;
if (a == b) return 0;
if (sdsEncodedObject(a)) {
astr = a->ptr;
alen = sdslen(astr);
} else {
alen = ll2string(bufa,sizeof(bufa),(long) a->ptr);
astr = bufa;
}
if (sdsEncodedObject(b)) {
bstr = b->ptr;
blen = sdslen(bstr);
} else {
blen = ll2string(bufb,sizeof(bufb),(long) b->ptr);
bstr = bufb;
}
if (flags & REDIS_COMPARE_COLL) {
return strcoll(astr,bstr);
} else {
int cmp;
minlen = (alen < blen) ? alen : blen;
cmp = memcmp(astr,bstr,minlen);
if (cmp == 0) return alen-blen;
return cmp;
}
}
/* Wrapper for compareStringObjectsWithFlags() using binary comparison. */
int compareStringObjects(robj *a, robj *b) {
return compareStringObjectsWithFlags(a,b,REDIS_COMPARE_BINARY);
}
/* Wrapper for compareStringObjectsWithFlags() using collation. */
int collateStringObjects(robj *a, robj *b) {
return compareStringObjectsWithFlags(a,b,REDIS_COMPARE_COLL);
}
/* Equal string objects return 1 if the two objects are the same from the
* point of view of a string comparison, otherwise 0 is returned. Note that
* this function is faster then checking for (compareStringObject(a,b) == 0)
* because it can perform some more optimization. */
int equalStringObjects(robj *a, robj *b) {
if (a->encoding == REDIS_ENCODING_INT &&
b->encoding == REDIS_ENCODING_INT){
/* If both strings are integer encoded just check if the stored
* long is the same. */
return a->ptr == b->ptr;
} else {
return compareStringObjects(a,b) == 0;
}
}
size_t stringObjectLen(robj *o) {
redisAssertWithInfo(NULL,o,o->type == REDIS_STRING);
if (sdsEncodedObject(o)) {
return sdslen(o->ptr);
} else {
return sdigits10((long)o->ptr);
}
}
int getDoubleFromObject(robj *o, double *target) {
double value;
char *eptr;
if (o == NULL) {
value = 0;
} else {
redisAssertWithInfo(NULL,o,o->type == REDIS_STRING);
if (sdsEncodedObject(o)) {
errno = 0;
value = strtod(o->ptr, &eptr);
if (isspace(((char*)o->ptr)[0]) ||
eptr[0] != '\0' ||
(errno == ERANGE &&
(value == HUGE_VAL || value == -HUGE_VAL || value == 0)) ||
errno == EINVAL ||
isnan(value))
return REDIS_ERR;
} else if (o->encoding == REDIS_ENCODING_INT) {
value = (long)o->ptr;
} else {
redisPanic("Unknown string encoding");
}
}
*target = value;
return REDIS_OK;
}
int getDoubleFromObjectOrReply(redisClient *c, robj *o, double *target, const char *msg) {
double value;
if (getDoubleFromObject(o, &value) != REDIS_OK) {
if (msg != NULL) {
addReplyError(c,(char*)msg);
} else {
addReplyError(c,"value is not a valid float");
}
return REDIS_ERR;
}
*target = value;
return REDIS_OK;
}
int getLongDoubleFromObject(robj *o, long double *target) {
long double value;
char *eptr;
if (o == NULL) {
value = 0;
} else {
redisAssertWithInfo(NULL,o,o->type == REDIS_STRING);
if (sdsEncodedObject(o)) {
errno = 0;
value = strtold(o->ptr, &eptr);
if (isspace(((char*)o->ptr)[0]) || eptr[0] != '\0' ||
errno == ERANGE || isnan(value))
return REDIS_ERR;
} else if (o->encoding == REDIS_ENCODING_INT) {
value = (long)o->ptr;
} else {
redisPanic("Unknown string encoding");
}
}
*target = value;
return REDIS_OK;
}
int getLongDoubleFromObjectOrReply(redisClient *c, robj *o, long double *target, const char *msg) {
long double value;
if (getLongDoubleFromObject(o, &value) != REDIS_OK) {
if (msg != NULL) {
addReplyError(c,(char*)msg);
} else {
addReplyError(c,"value is not a valid float");
}
return REDIS_ERR;
}
*target = value;
return REDIS_OK;
}
int getLongLongFromObject(robj *o, long long *target) {
long long value;
char *eptr;
if (o == NULL) {
value = 0;
} else {
redisAssertWithInfo(NULL,o,o->type == REDIS_STRING);
if (sdsEncodedObject(o)) {
errno = 0;
value = strtoll(o->ptr, &eptr, 10);
if (isspace(((char*)o->ptr)[0]) || eptr[0] != '\0' ||
errno == ERANGE)
return REDIS_ERR;
} else if (o->encoding == REDIS_ENCODING_INT) {
value = (long)o->ptr;
} else {
redisPanic("Unknown string encoding");
}
}
if (target) *target = value;
return REDIS_OK;
}
int getLongLongFromObjectOrReply(redisClient *c, robj *o, long long *target, const char *msg) {
long long value;
if (getLongLongFromObject(o, &value) != REDIS_OK) {
if (msg != NULL) {
addReplyError(c,(char*)msg);
} else {
addReplyError(c,"value is not an integer or out of range");
}
return REDIS_ERR;
}
*target = value;
return REDIS_OK;
}
int getLongFromObjectOrReply(redisClient *c, robj *o, long *target, const char *msg) {
long long value;
if (getLongLongFromObjectOrReply(c, o, &value, msg) != REDIS_OK) return REDIS_ERR;
if (value < LONG_MIN || value > LONG_MAX) {
if (msg != NULL) {
addReplyError(c,(char*)msg);
} else {
addReplyError(c,"value is out of range");
}
return REDIS_ERR;
}
*target = value;
return REDIS_OK;
}
char *strEncoding(int encoding) {
switch(encoding) {
case REDIS_ENCODING_RAW: return "raw";
case REDIS_ENCODING_INT: return "int";
case REDIS_ENCODING_HT: return "hashtable";
case REDIS_ENCODING_QUICKLIST: return "quicklist";
case REDIS_ENCODING_ZIPLIST: return "ziplist";
case REDIS_ENCODING_INTSET: return "intset";
case REDIS_ENCODING_SKIPLIST: return "skiplist";
case REDIS_ENCODING_EMBSTR: return "embstr";
default: return "unknown";
}
}
/* Given an object returns the min number of milliseconds the object was never
* requested, using an approximated LRU algorithm. */
unsigned long long estimateObjectIdleTime(robj *o) {
unsigned long long lruclock = LRU_CLOCK();
if (lruclock >= o->lru) {
return (lruclock - o->lru) * REDIS_LRU_CLOCK_RESOLUTION;
} else {
return (lruclock + (REDIS_LRU_CLOCK_MAX - o->lru)) *
REDIS_LRU_CLOCK_RESOLUTION;
}
}
/* This is a helper function for the OBJECT command. We need to lookup keys
* without any modification of LRU or other parameters. */
robj *objectCommandLookup(redisClient *c, robj *key) {
dictEntry *de;
if ((de = dictFind(c->db->dict,key->ptr)) == NULL) return NULL;
return (robj*) dictGetVal(de);
}
robj *objectCommandLookupOrReply(redisClient *c, robj *key, robj *reply) {
robj *o = objectCommandLookup(c,key);
if (!o) addReply(c, reply);
return o;
}
/* Object command allows to inspect the internals of an Redis Object.
* Usage: OBJECT <refcount|encoding|idletime> <key> */
void objectCommand(redisClient *c) {
robj *o;
if (!strcasecmp(c->argv[1]->ptr,"refcount") && c->argc == 3) {
if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
== NULL) return;
addReplyLongLong(c,o->refcount);
} else if (!strcasecmp(c->argv[1]->ptr,"encoding") && c->argc == 3) {
if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
== NULL) return;
addReplyBulkCString(c,strEncoding(o->encoding));
} else if (!strcasecmp(c->argv[1]->ptr,"idletime") && c->argc == 3) {
if ((o = objectCommandLookupOrReply(c,c->argv[2],shared.nullbulk))
== NULL) return;
addReplyLongLong(c,estimateObjectIdleTime(o)/1000);
} else {
addReplyError(c,"Syntax error. Try OBJECT (refcount|encoding|idletime)");
}
}
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