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redict/src/t_list.c

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/*
* 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 "redis.h"
/*-----------------------------------------------------------------------------
* List API
*----------------------------------------------------------------------------*/
/* Check the argument length to see if it requires us to convert the ziplist
* to a real list. Only check raw-encoded objects because integer encoded
* objects are never too long. */
void listTypeTryConversion(robj *subject, robj *value) {
if (subject->encoding != REDIS_ENCODING_ZIPLIST) return;
if (sdsEncodedObject(value) &&
sdslen(value->ptr) > server.list_max_ziplist_value)
listTypeConvert(subject,REDIS_ENCODING_LINKEDLIST);
}
/* The function pushes an element to the specified list object 'subject',
* at head or tail position as specified by 'where'.
*
* There is no need for the caller to increment the refcount of 'value' as
* the function takes care of it if needed. */
void listTypePush(robj *subject, robj *value, int where) {
/* Check if we need to convert the ziplist */
listTypeTryConversion(subject,value);
if (subject->encoding == REDIS_ENCODING_ZIPLIST &&
ziplistLen(subject->ptr) >= server.list_max_ziplist_entries)
listTypeConvert(subject,REDIS_ENCODING_LINKEDLIST);
if (subject->encoding == REDIS_ENCODING_ZIPLIST) {
int pos = (where == REDIS_HEAD) ? ZIPLIST_HEAD : ZIPLIST_TAIL;
value = getDecodedObject(value);
subject->ptr = ziplistPush(subject->ptr,value->ptr,sdslen(value->ptr),pos);
decrRefCount(value);
} else if (subject->encoding == REDIS_ENCODING_LINKEDLIST) {
if (where == REDIS_HEAD) {
listAddNodeHead(subject->ptr,value);
} else {
listAddNodeTail(subject->ptr,value);
}
incrRefCount(value);
} else {
redisPanic("Unknown list encoding");
}
}
robj *listTypePop(robj *subject, int where) {
robj *value = NULL;
if (subject->encoding == REDIS_ENCODING_ZIPLIST) {
unsigned char *p;
unsigned char *vstr;
unsigned int vlen;
long long vlong;
int pos = (where == REDIS_HEAD) ? 0 : -1;
p = ziplistIndex(subject->ptr,pos);
if (ziplistGet(p,&vstr,&vlen,&vlong)) {
if (vstr) {
value = createStringObject((char*)vstr,vlen);
} else {
value = createStringObjectFromLongLong(vlong);
}
/* We only need to delete an element when it exists */
subject->ptr = ziplistDelete(subject->ptr,&p);
}
} else if (subject->encoding == REDIS_ENCODING_LINKEDLIST) {
list *list = subject->ptr;
listNode *ln;
if (where == REDIS_HEAD) {
ln = listFirst(list);
} else {
ln = listLast(list);
}
if (ln != NULL) {
value = listNodeValue(ln);
incrRefCount(value);
listDelNode(list,ln);
}
} else {
redisPanic("Unknown list encoding");
}
return value;
}
unsigned long listTypeLength(robj *subject) {
if (subject->encoding == REDIS_ENCODING_ZIPLIST) {
return ziplistLen(subject->ptr);
} else if (subject->encoding == REDIS_ENCODING_LINKEDLIST) {
return listLength((list*)subject->ptr);
} else {
redisPanic("Unknown list encoding");
}
}
/* Initialize an iterator at the specified index. */
listTypeIterator *listTypeInitIterator(robj *subject, long index, unsigned char direction) {
listTypeIterator *li = zmalloc(sizeof(listTypeIterator));
li->subject = subject;
li->encoding = subject->encoding;
li->direction = direction;
if (li->encoding == REDIS_ENCODING_ZIPLIST) {
li->zi = ziplistIndex(subject->ptr,index);
} else if (li->encoding == REDIS_ENCODING_LINKEDLIST) {
li->ln = listIndex(subject->ptr,index);
} else {
redisPanic("Unknown list encoding");
}
return li;
}
/* Clean up the iterator. */
void listTypeReleaseIterator(listTypeIterator *li) {
zfree(li);
}
/* Stores pointer to current the entry in the provided entry structure
* and advances the position of the iterator. Returns 1 when the current
* entry is in fact an entry, 0 otherwise. */
int listTypeNext(listTypeIterator *li, listTypeEntry *entry) {
/* Protect from converting when iterating */
redisAssert(li->subject->encoding == li->encoding);
entry->li = li;
if (li->encoding == REDIS_ENCODING_ZIPLIST) {
entry->zi = li->zi;
if (entry->zi != NULL) {
if (li->direction == REDIS_TAIL)
li->zi = ziplistNext(li->subject->ptr,li->zi);
else
li->zi = ziplistPrev(li->subject->ptr,li->zi);
return 1;
}
} else if (li->encoding == REDIS_ENCODING_LINKEDLIST) {
entry->ln = li->ln;
if (entry->ln != NULL) {
if (li->direction == REDIS_TAIL)
li->ln = li->ln->next;
else
li->ln = li->ln->prev;
return 1;
}
} else {
redisPanic("Unknown list encoding");
}
return 0;
}
/* Return entry or NULL at the current position of the iterator. */
robj *listTypeGet(listTypeEntry *entry) {
listTypeIterator *li = entry->li;
robj *value = NULL;
if (li->encoding == REDIS_ENCODING_ZIPLIST) {
unsigned char *vstr;
unsigned int vlen;
long long vlong;
redisAssert(entry->zi != NULL);
if (ziplistGet(entry->zi,&vstr,&vlen,&vlong)) {
if (vstr) {
value = createStringObject((char*)vstr,vlen);
} else {
value = createStringObjectFromLongLong(vlong);
}
}
} else if (li->encoding == REDIS_ENCODING_LINKEDLIST) {
redisAssert(entry->ln != NULL);
value = listNodeValue(entry->ln);
incrRefCount(value);
} else {
redisPanic("Unknown list encoding");
}
return value;
}
void listTypeInsert(listTypeEntry *entry, robj *value, int where) {
robj *subject = entry->li->subject;
if (entry->li->encoding == REDIS_ENCODING_ZIPLIST) {
value = getDecodedObject(value);
if (where == REDIS_TAIL) {
unsigned char *next = ziplistNext(subject->ptr,entry->zi);
/* When we insert after the current element, but the current element
* is the tail of the list, we need to do a push. */
if (next == NULL) {
subject->ptr = ziplistPush(subject->ptr,value->ptr,sdslen(value->ptr),REDIS_TAIL);
} else {
subject->ptr = ziplistInsert(subject->ptr,next,value->ptr,sdslen(value->ptr));
}
} else {
subject->ptr = ziplistInsert(subject->ptr,entry->zi,value->ptr,sdslen(value->ptr));
}
decrRefCount(value);
} else if (entry->li->encoding == REDIS_ENCODING_LINKEDLIST) {
if (where == REDIS_TAIL) {
listInsertNode(subject->ptr,entry->ln,value,AL_START_TAIL);
} else {
listInsertNode(subject->ptr,entry->ln,value,AL_START_HEAD);
}
incrRefCount(value);
} else {
redisPanic("Unknown list encoding");
}
}
/* Compare the given object with the entry at the current position. */
int listTypeEqual(listTypeEntry *entry, robj *o) {
listTypeIterator *li = entry->li;
if (li->encoding == REDIS_ENCODING_ZIPLIST) {
redisAssertWithInfo(NULL,o,sdsEncodedObject(o));
return ziplistCompare(entry->zi,o->ptr,sdslen(o->ptr));
} else if (li->encoding == REDIS_ENCODING_LINKEDLIST) {
return equalStringObjects(o,listNodeValue(entry->ln));
} else {
redisPanic("Unknown list encoding");
}
}
/* Delete the element pointed to. */
void listTypeDelete(listTypeEntry *entry) {
listTypeIterator *li = entry->li;
if (li->encoding == REDIS_ENCODING_ZIPLIST) {
unsigned char *p = entry->zi;
li->subject->ptr = ziplistDelete(li->subject->ptr,&p);
/* Update position of the iterator depending on the direction */
if (li->direction == REDIS_TAIL)
li->zi = p;
else
li->zi = ziplistPrev(li->subject->ptr,p);
} else if (entry->li->encoding == REDIS_ENCODING_LINKEDLIST) {
listNode *next;
if (li->direction == REDIS_TAIL)
next = entry->ln->next;
else
next = entry->ln->prev;
listDelNode(li->subject->ptr,entry->ln);
li->ln = next;
} else {
redisPanic("Unknown list encoding");
}
}
void listTypeConvert(robj *subject, int enc) {
listTypeIterator *li;
listTypeEntry entry;
redisAssertWithInfo(NULL,subject,subject->type == REDIS_LIST);
if (enc == REDIS_ENCODING_LINKEDLIST) {
list *l = listCreate();
listSetFreeMethod(l,decrRefCountVoid);
/* listTypeGet returns a robj with incremented refcount */
li = listTypeInitIterator(subject,0,REDIS_TAIL);
while (listTypeNext(li,&entry)) listAddNodeTail(l,listTypeGet(&entry));
listTypeReleaseIterator(li);
subject->encoding = REDIS_ENCODING_LINKEDLIST;
zfree(subject->ptr);
subject->ptr = l;
} else {
redisPanic("Unsupported list conversion");
}
}
/*-----------------------------------------------------------------------------
* List Commands
*----------------------------------------------------------------------------*/
void pushGenericCommand(redisClient *c, int where) {
int j, waiting = 0, pushed = 0;
robj *lobj = lookupKeyWrite(c->db,c->argv[1]);
if (lobj && lobj->type != REDIS_LIST) {
addReply(c,shared.wrongtypeerr);
return;
}
for (j = 2; j < c->argc; j++) {
c->argv[j] = tryObjectEncoding(c->argv[j]);
if (!lobj) {
lobj = createZiplistObject();
dbAdd(c->db,c->argv[1],lobj);
}
listTypePush(lobj,c->argv[j],where);
pushed++;
}
addReplyLongLong(c, waiting + (lobj ? listTypeLength(lobj) : 0));
if (pushed) {
char *event = (where == REDIS_HEAD) ? "lpush" : "rpush";
signalModifiedKey(c->db,c->argv[1]);
notifyKeyspaceEvent(REDIS_NOTIFY_LIST,event,c->argv[1],c->db->id);
}
server.dirty += pushed;
}
void lpushCommand(redisClient *c) {
pushGenericCommand(c,REDIS_HEAD);
}
void rpushCommand(redisClient *c) {
pushGenericCommand(c,REDIS_TAIL);
}
void pushxGenericCommand(redisClient *c, robj *refval, robj *val, int where) {
robj *subject;
listTypeIterator *iter;
listTypeEntry entry;
int inserted = 0;
if ((subject = lookupKeyReadOrReply(c,c->argv[1],shared.czero)) == NULL ||
checkType(c,subject,REDIS_LIST)) return;
if (refval != NULL) {
/* We're not sure if this value can be inserted yet, but we cannot
* convert the list inside the iterator. We don't want to loop over
* the list twice (once to see if the value can be inserted and once
* to do the actual insert), so we assume this value can be inserted
* and convert the ziplist to a regular list if necessary. */
listTypeTryConversion(subject,val);
/* Seek refval from head to tail */
iter = listTypeInitIterator(subject,0,REDIS_TAIL);
while (listTypeNext(iter,&entry)) {
if (listTypeEqual(&entry,refval)) {
listTypeInsert(&entry,val,where);
inserted = 1;
break;
}
}
listTypeReleaseIterator(iter);
if (inserted) {
/* Check if the length exceeds the ziplist length threshold. */
if (subject->encoding == REDIS_ENCODING_ZIPLIST &&
ziplistLen(subject->ptr) > server.list_max_ziplist_entries)
listTypeConvert(subject,REDIS_ENCODING_LINKEDLIST);
signalModifiedKey(c->db,c->argv[1]);
notifyKeyspaceEvent(REDIS_NOTIFY_LIST,"linsert",
c->argv[1],c->db->id);
server.dirty++;
} else {
/* Notify client of a failed insert */
addReply(c,shared.cnegone);
return;
}
} else {
char *event = (where == REDIS_HEAD) ? "lpush" : "rpush";
listTypePush(subject,val,where);
signalModifiedKey(c->db,c->argv[1]);
notifyKeyspaceEvent(REDIS_NOTIFY_LIST,event,c->argv[1],c->db->id);
server.dirty++;
}
addReplyLongLong(c,listTypeLength(subject));
}
void lpushxCommand(redisClient *c) {
c->argv[2] = tryObjectEncoding(c->argv[2]);
pushxGenericCommand(c,NULL,c->argv[2],REDIS_HEAD);
}
void rpushxCommand(redisClient *c) {
c->argv[2] = tryObjectEncoding(c->argv[2]);
pushxGenericCommand(c,NULL,c->argv[2],REDIS_TAIL);
}
void linsertCommand(redisClient *c) {
c->argv[4] = tryObjectEncoding(c->argv[4]);
if (strcasecmp(c->argv[2]->ptr,"after") == 0) {
pushxGenericCommand(c,c->argv[3],c->argv[4],REDIS_TAIL);
} else if (strcasecmp(c->argv[2]->ptr,"before") == 0) {
pushxGenericCommand(c,c->argv[3],c->argv[4],REDIS_HEAD);
} else {
addReply(c,shared.syntaxerr);
}
}
void llenCommand(redisClient *c) {
robj *o = lookupKeyReadOrReply(c,c->argv[1],shared.czero);
if (o == NULL || checkType(c,o,REDIS_LIST)) return;
addReplyLongLong(c,listTypeLength(o));
}
void lindexCommand(redisClient *c) {
robj *o = lookupKeyReadOrReply(c,c->argv[1],shared.nullbulk);
if (o == NULL || checkType(c,o,REDIS_LIST)) return;
long index;
robj *value = NULL;
if ((getLongFromObjectOrReply(c, c->argv[2], &index, NULL) != REDIS_OK))
return;
if (o->encoding == REDIS_ENCODING_ZIPLIST) {
unsigned char *p;
unsigned char *vstr;
unsigned int vlen;
long long vlong;
p = ziplistIndex(o->ptr,index);
if (ziplistGet(p,&vstr,&vlen,&vlong)) {
if (vstr) {
value = createStringObject((char*)vstr,vlen);
} else {
value = createStringObjectFromLongLong(vlong);
}
addReplyBulk(c,value);
decrRefCount(value);
} else {
addReply(c,shared.nullbulk);
}
} else if (o->encoding == REDIS_ENCODING_LINKEDLIST) {
listNode *ln = listIndex(o->ptr,index);
if (ln != NULL) {
value = listNodeValue(ln);
addReplyBulk(c,value);
} else {
addReply(c,shared.nullbulk);
}
} else {
redisPanic("Unknown list encoding");
}
}
void lsetCommand(redisClient *c) {
robj *o = lookupKeyWriteOrReply(c,c->argv[1],shared.nokeyerr);
if (o == NULL || checkType(c,o,REDIS_LIST)) return;
long index;
robj *value = (c->argv[3] = tryObjectEncoding(c->argv[3]));
if ((getLongFromObjectOrReply(c, c->argv[2], &index, NULL) != REDIS_OK))
return;
listTypeTryConversion(o,value);
if (o->encoding == REDIS_ENCODING_ZIPLIST) {
unsigned char *p, *zl = o->ptr;
p = ziplistIndex(zl,index);
if (p == NULL) {
addReply(c,shared.outofrangeerr);
} else {
o->ptr = ziplistDelete(o->ptr,&p);
value = getDecodedObject(value);
o->ptr = ziplistInsert(o->ptr,p,value->ptr,sdslen(value->ptr));
decrRefCount(value);
addReply(c,shared.ok);
signalModifiedKey(c->db,c->argv[1]);
notifyKeyspaceEvent(REDIS_NOTIFY_LIST,"lset",c->argv[1],c->db->id);
server.dirty++;
}
} else if (o->encoding == REDIS_ENCODING_LINKEDLIST) {
listNode *ln = listIndex(o->ptr,index);
if (ln == NULL) {
addReply(c,shared.outofrangeerr);
} else {
decrRefCount((robj*)listNodeValue(ln));
listNodeValue(ln) = value;
incrRefCount(value);
addReply(c,shared.ok);
signalModifiedKey(c->db,c->argv[1]);
notifyKeyspaceEvent(REDIS_NOTIFY_LIST,"lset",c->argv[1],c->db->id);
server.dirty++;
}
} else {
redisPanic("Unknown list encoding");
}
}
void popGenericCommand(redisClient *c, int where) {
robj *o = lookupKeyWriteOrReply(c,c->argv[1],shared.nullbulk);
if (o == NULL || checkType(c,o,REDIS_LIST)) return;
robj *value = listTypePop(o,where);
if (value == NULL) {
addReply(c,shared.nullbulk);
} else {
char *event = (where == REDIS_HEAD) ? "lpop" : "rpop";
addReplyBulk(c,value);
decrRefCount(value);
notifyKeyspaceEvent(REDIS_NOTIFY_LIST,event,c->argv[1],c->db->id);
if (listTypeLength(o) == 0) {
notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",
c->argv[1],c->db->id);
dbDelete(c->db,c->argv[1]);
}
signalModifiedKey(c->db,c->argv[1]);
server.dirty++;
}
}
void lpopCommand(redisClient *c) {
popGenericCommand(c,REDIS_HEAD);
}
void rpopCommand(redisClient *c) {
popGenericCommand(c,REDIS_TAIL);
}
void lrangeCommand(redisClient *c) {
robj *o;
long start, end, llen, rangelen;
if ((getLongFromObjectOrReply(c, c->argv[2], &start, NULL) != REDIS_OK) ||
(getLongFromObjectOrReply(c, c->argv[3], &end, NULL) != REDIS_OK)) return;
if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.emptymultibulk)) == NULL
|| checkType(c,o,REDIS_LIST)) return;
llen = listTypeLength(o);
/* convert negative indexes */
if (start < 0) start = llen+start;
if (end < 0) end = llen+end;
if (start < 0) start = 0;
/* Invariant: start >= 0, so this test will be true when end < 0.
* The range is empty when start > end or start >= length. */
if (start > end || start >= llen) {
addReply(c,shared.emptymultibulk);
return;
}
if (end >= llen) end = llen-1;
rangelen = (end-start)+1;
/* Return the result in form of a multi-bulk reply */
addReplyMultiBulkLen(c,rangelen);
if (o->encoding == REDIS_ENCODING_ZIPLIST) {
unsigned char *p = ziplistIndex(o->ptr,start);
unsigned char *vstr;
unsigned int vlen;
long long vlong;
while(rangelen--) {
ziplistGet(p,&vstr,&vlen,&vlong);
if (vstr) {
addReplyBulkCBuffer(c,vstr,vlen);
} else {
addReplyBulkLongLong(c,vlong);
}
p = ziplistNext(o->ptr,p);
}
} else if (o->encoding == REDIS_ENCODING_LINKEDLIST) {
listNode *ln;
/* If we are nearest to the end of the list, reach the element
* starting from tail and going backward, as it is faster. */
if (start > llen/2) start -= llen;
ln = listIndex(o->ptr,start);
while(rangelen--) {
addReplyBulk(c,ln->value);
ln = ln->next;
}
} else {
redisPanic("List encoding is not LINKEDLIST nor ZIPLIST!");
}
}
void ltrimCommand(redisClient *c) {
robj *o;
long start, end, llen, j, ltrim, rtrim;
list *list;
listNode *ln;
if ((getLongFromObjectOrReply(c, c->argv[2], &start, NULL) != REDIS_OK) ||
(getLongFromObjectOrReply(c, c->argv[3], &end, NULL) != REDIS_OK)) return;
if ((o = lookupKeyWriteOrReply(c,c->argv[1],shared.ok)) == NULL ||
checkType(c,o,REDIS_LIST)) return;
llen = listTypeLength(o);
/* convert negative indexes */
if (start < 0) start = llen+start;
if (end < 0) end = llen+end;
if (start < 0) start = 0;
/* Invariant: start >= 0, so this test will be true when end < 0.
* The range is empty when start > end or start >= length. */
if (start > end || start >= llen) {
/* Out of range start or start > end result in empty list */
ltrim = llen;
rtrim = 0;
} else {
if (end >= llen) end = llen-1;
ltrim = start;
rtrim = llen-end-1;
}
/* Remove list elements to perform the trim */
if (o->encoding == REDIS_ENCODING_ZIPLIST) {
o->ptr = ziplistDeleteRange(o->ptr,0,ltrim);
o->ptr = ziplistDeleteRange(o->ptr,-rtrim,rtrim);
} else if (o->encoding == REDIS_ENCODING_LINKEDLIST) {
list = o->ptr;
for (j = 0; j < ltrim; j++) {
ln = listFirst(list);
listDelNode(list,ln);
}
for (j = 0; j < rtrim; j++) {
ln = listLast(list);
listDelNode(list,ln);
}
} else {
redisPanic("Unknown list encoding");
}
notifyKeyspaceEvent(REDIS_NOTIFY_LIST,"ltrim",c->argv[1],c->db->id);
if (listTypeLength(o) == 0) {
dbDelete(c->db,c->argv[1]);
notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",c->argv[1],c->db->id);
}
signalModifiedKey(c->db,c->argv[1]);
server.dirty++;
addReply(c,shared.ok);
}
void lremCommand(redisClient *c) {
robj *subject, *obj;
obj = c->argv[3] = tryObjectEncoding(c->argv[3]);
long toremove;
long removed = 0;
listTypeEntry entry;
if ((getLongFromObjectOrReply(c, c->argv[2], &toremove, NULL) != REDIS_OK))
return;
subject = lookupKeyWriteOrReply(c,c->argv[1],shared.czero);
if (subject == NULL || checkType(c,subject,REDIS_LIST)) return;
/* Make sure obj is raw when we're dealing with a ziplist */
if (subject->encoding == REDIS_ENCODING_ZIPLIST)
obj = getDecodedObject(obj);
listTypeIterator *li;
if (toremove < 0) {
toremove = -toremove;
li = listTypeInitIterator(subject,-1,REDIS_HEAD);
} else {
li = listTypeInitIterator(subject,0,REDIS_TAIL);
}
while (listTypeNext(li,&entry)) {
if (listTypeEqual(&entry,obj)) {
listTypeDelete(&entry);
server.dirty++;
removed++;
if (toremove && removed == toremove) break;
}
}
listTypeReleaseIterator(li);
/* Clean up raw encoded object */
if (subject->encoding == REDIS_ENCODING_ZIPLIST)
decrRefCount(obj);
if (listTypeLength(subject) == 0) dbDelete(c->db,c->argv[1]);
addReplyLongLong(c,removed);
if (removed) signalModifiedKey(c->db,c->argv[1]);
}
/* This is the semantic of this command:
* RPOPLPUSH srclist dstlist:
* IF LLEN(srclist) > 0
* element = RPOP srclist
* LPUSH dstlist element
* RETURN element
* ELSE
* RETURN nil
* END
* END
*
* The idea is to be able to get an element from a list in a reliable way
* since the element is not just returned but pushed against another list
* as well. This command was originally proposed by Ezra Zygmuntowicz.
*/
void rpoplpushHandlePush(redisClient *c, robj *dstkey, robj *dstobj, robj *value) {
/* Create the list if the key does not exist */
if (!dstobj) {
dstobj = createZiplistObject();
dbAdd(c->db,dstkey,dstobj);
}
signalModifiedKey(c->db,dstkey);
listTypePush(dstobj,value,REDIS_HEAD);
notifyKeyspaceEvent(REDIS_NOTIFY_LIST,"lpush",dstkey,c->db->id);
/* Always send the pushed value to the client. */
addReplyBulk(c,value);
}
void rpoplpushCommand(redisClient *c) {
robj *sobj, *value;
if ((sobj = lookupKeyWriteOrReply(c,c->argv[1],shared.nullbulk)) == NULL ||
checkType(c,sobj,REDIS_LIST)) return;
if (listTypeLength(sobj) == 0) {
/* This may only happen after loading very old RDB files. Recent
* versions of Redis delete keys of empty lists. */
addReply(c,shared.nullbulk);
} else {
robj *dobj = lookupKeyWrite(c->db,c->argv[2]);
robj *touchedkey = c->argv[1];
if (dobj && checkType(c,dobj,REDIS_LIST)) return;
value = listTypePop(sobj,REDIS_TAIL);
/* We saved touched key, and protect it, since rpoplpushHandlePush
* may change the client command argument vector (it does not
* currently). */
incrRefCount(touchedkey);
rpoplpushHandlePush(c,c->argv[2],dobj,value);
/* listTypePop returns an object with its refcount incremented */
decrRefCount(value);
/* Delete the source list when it is empty */
notifyKeyspaceEvent(REDIS_NOTIFY_LIST,"rpop",touchedkey,c->db->id);
if (listTypeLength(sobj) == 0) {
dbDelete(c->db,touchedkey);
notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",
touchedkey,c->db->id);
}
signalModifiedKey(c->db,touchedkey);
decrRefCount(touchedkey);
server.dirty++;
}
}
/*-----------------------------------------------------------------------------
* Blocking POP operations
*----------------------------------------------------------------------------*/
/* This is how the current blocking POP works, we use BLPOP as example:
* - If the user calls BLPOP and the key exists and contains a non empty list
* then LPOP is called instead. So BLPOP is semantically the same as LPOP
* if blocking is not required.
* - If instead BLPOP is called and the key does not exists or the list is
* empty we need to block. In order to do so we remove the notification for
* new data to read in the client socket (so that we'll not serve new
* requests if the blocking request is not served). Also we put the client
* in a dictionary (db->blocking_keys) mapping keys to a list of clients
* blocking for this keys.
* - If a PUSH operation against a key with blocked clients waiting is
* performed, we mark this key as "ready", and after the current command,
* MULTI/EXEC block, or script, is executed, we serve all the clients waiting
* for this list, from the one that blocked first, to the last, accordingly
* to the number of elements we have in the ready list.
*/
/* Set a client in blocking mode for the specified key, with the specified
* timeout */
void blockForKeys(redisClient *c, robj **keys, int numkeys, mstime_t timeout, robj *target) {
dictEntry *de;
list *l;
int j;
c->bpop.timeout = timeout;
c->bpop.target = target;
if (target != NULL) incrRefCount(target);
for (j = 0; j < numkeys; j++) {
/* If the key already exists in the dict ignore it. */
if (dictAdd(c->bpop.keys,keys[j],NULL) != DICT_OK) continue;
incrRefCount(keys[j]);
/* And in the other "side", to map keys -> clients */
de = dictFind(c->db->blocking_keys,keys[j]);
if (de == NULL) {
int retval;
/* For every key we take a list of clients blocked for it */
l = listCreate();
retval = dictAdd(c->db->blocking_keys,keys[j],l);
incrRefCount(keys[j]);
redisAssertWithInfo(c,keys[j],retval == DICT_OK);
} else {
l = dictGetVal(de);
}
listAddNodeTail(l,c);
}
blockClient(c,REDIS_BLOCKED_LIST);
}
/* Unblock a client that's waiting in a blocking operation such as BLPOP.
* You should never call this function directly, but unblockClient() instead. */
void unblockClientWaitingData(redisClient *c) {
dictEntry *de;
dictIterator *di;
list *l;
redisAssertWithInfo(c,NULL,dictSize(c->bpop.keys) != 0);
di = dictGetIterator(c->bpop.keys);
/* The client may wait for multiple keys, so unblock it for every key. */
while((de = dictNext(di)) != NULL) {
robj *key = dictGetKey(de);
/* Remove this client from the list of clients waiting for this key. */
l = dictFetchValue(c->db->blocking_keys,key);
redisAssertWithInfo(c,key,l != NULL);
listDelNode(l,listSearchKey(l,c));
/* If the list is empty we need to remove it to avoid wasting memory */
if (listLength(l) == 0)
dictDelete(c->db->blocking_keys,key);
}
dictReleaseIterator(di);
/* Cleanup the client structure */
dictEmpty(c->bpop.keys,NULL);
if (c->bpop.target) {
decrRefCount(c->bpop.target);
c->bpop.target = NULL;
}
}
/* If the specified key has clients blocked waiting for list pushes, this
* function will put the key reference into the server.ready_keys list.
* Note that db->ready_keys is a hash table that allows us to avoid putting
* the same key again and again in the list in case of multiple pushes
* made by a script or in the context of MULTI/EXEC.
*
* The list will be finally processed by handleClientsBlockedOnLists() */
void signalListAsReady(redisDb *db, robj *key) {
readyList *rl;
/* No clients blocking for this key? No need to queue it. */
if (dictFind(db->blocking_keys,key) == NULL) return;
/* Key was already signaled? No need to queue it again. */
if (dictFind(db->ready_keys,key) != NULL) return;
/* Ok, we need to queue this key into server.ready_keys. */
rl = zmalloc(sizeof(*rl));
rl->key = key;
rl->db = db;
incrRefCount(key);
listAddNodeTail(server.ready_keys,rl);
/* We also add the key in the db->ready_keys dictionary in order
* to avoid adding it multiple times into a list with a simple O(1)
* check. */
incrRefCount(key);
redisAssert(dictAdd(db->ready_keys,key,NULL) == DICT_OK);
}
/* This is a helper function for handleClientsBlockedOnLists(). It's work
* is to serve a specific client (receiver) that is blocked on 'key'
* in the context of the specified 'db', doing the following:
*
* 1) Provide the client with the 'value' element.
* 2) If the dstkey is not NULL (we are serving a BRPOPLPUSH) also push the
* 'value' element on the destination list (the LPUSH side of the command).
* 3) Propagate the resulting BRPOP, BLPOP and additional LPUSH if any into
* the AOF and replication channel.
*
* The argument 'where' is REDIS_TAIL or REDIS_HEAD, and indicates if the
* 'value' element was popped fron the head (BLPOP) or tail (BRPOP) so that
* we can propagate the command properly.
*
* The function returns REDIS_OK if we are able to serve the client, otherwise
* REDIS_ERR is returned to signal the caller that the list POP operation
* should be undone as the client was not served: This only happens for
* BRPOPLPUSH that fails to push the value to the destination key as it is
* of the wrong type. */
int serveClientBlockedOnList(redisClient *receiver, robj *key, robj *dstkey, redisDb *db, robj *value, int where)
{
robj *argv[3];
if (dstkey == NULL) {
/* Propagate the [LR]POP operation. */
argv[0] = (where == REDIS_HEAD) ? shared.lpop :
shared.rpop;
argv[1] = key;
propagate((where == REDIS_HEAD) ?
server.lpopCommand : server.rpopCommand,
db->id,argv,2,REDIS_PROPAGATE_AOF|REDIS_PROPAGATE_REPL);
/* BRPOP/BLPOP */
addReplyMultiBulkLen(receiver,2);
addReplyBulk(receiver,key);
addReplyBulk(receiver,value);
} else {
/* BRPOPLPUSH */
robj *dstobj =
lookupKeyWrite(receiver->db,dstkey);
if (!(dstobj &&
checkType(receiver,dstobj,REDIS_LIST)))
{
/* Propagate the RPOP operation. */
argv[0] = shared.rpop;
argv[1] = key;
propagate(server.rpopCommand,
db->id,argv,2,
REDIS_PROPAGATE_AOF|
REDIS_PROPAGATE_REPL);
rpoplpushHandlePush(receiver,dstkey,dstobj,
value);
/* Propagate the LPUSH operation. */
argv[0] = shared.lpush;
argv[1] = dstkey;
argv[2] = value;
propagate(server.lpushCommand,
db->id,argv,3,
REDIS_PROPAGATE_AOF|
REDIS_PROPAGATE_REPL);
} else {
/* BRPOPLPUSH failed because of wrong
* destination type. */
return REDIS_ERR;
}
}
return REDIS_OK;
}
/* This function should be called by Redis every time a single command,
* a MULTI/EXEC block, or a Lua script, terminated its execution after
* being called by a client.
*
* All the keys with at least one client blocked that received at least
* one new element via some PUSH operation are accumulated into
* the server.ready_keys list. This function will run the list and will
* serve clients accordingly. Note that the function will iterate again and
* again as a result of serving BRPOPLPUSH we can have new blocking clients
* to serve because of the PUSH side of BRPOPLPUSH. */
void handleClientsBlockedOnLists(void) {
while(listLength(server.ready_keys) != 0) {
list *l;
/* Point server.ready_keys to a fresh list and save the current one
* locally. This way as we run the old list we are free to call
* signalListAsReady() that may push new elements in server.ready_keys
* when handling clients blocked into BRPOPLPUSH. */
l = server.ready_keys;
server.ready_keys = listCreate();
while(listLength(l) != 0) {
listNode *ln = listFirst(l);
readyList *rl = ln->value;
/* First of all remove this key from db->ready_keys so that
* we can safely call signalListAsReady() against this key. */
dictDelete(rl->db->ready_keys,rl->key);
/* If the key exists and it's a list, serve blocked clients
* with data. */
robj *o = lookupKeyWrite(rl->db,rl->key);
if (o != NULL && o->type == REDIS_LIST) {
dictEntry *de;
/* We serve clients in the same order they blocked for
* this key, from the first blocked to the last. */
de = dictFind(rl->db->blocking_keys,rl->key);
if (de) {
list *clients = dictGetVal(de);
int numclients = listLength(clients);
while(numclients--) {
listNode *clientnode = listFirst(clients);
redisClient *receiver = clientnode->value;
robj *dstkey = receiver->bpop.target;
int where = (receiver->lastcmd &&
receiver->lastcmd->proc == blpopCommand) ?
REDIS_HEAD : REDIS_TAIL;
robj *value = listTypePop(o,where);
if (value) {
/* Protect receiver->bpop.target, that will be
* freed by the next unblockClient()
* call. */
if (dstkey) incrRefCount(dstkey);
unblockClient(receiver);
if (serveClientBlockedOnList(receiver,
rl->key,dstkey,rl->db,value,
where) == REDIS_ERR)
{
/* If we failed serving the client we need
* to also undo the POP operation. */
listTypePush(o,value,where);
}
if (dstkey) decrRefCount(dstkey);
decrRefCount(value);
} else {
break;
}
}
}
if (listTypeLength(o) == 0) dbDelete(rl->db,rl->key);
/* We don't call signalModifiedKey() as it was already called
* when an element was pushed on the list. */
}
/* Free this item. */
decrRefCount(rl->key);
zfree(rl);
listDelNode(l,ln);
}
listRelease(l); /* We have the new list on place at this point. */
}
}
/* Blocking RPOP/LPOP */
void blockingPopGenericCommand(redisClient *c, int where) {
robj *o;
mstime_t timeout;
int j;
if (getTimeoutFromObjectOrReply(c,c->argv[c->argc-1],&timeout,UNIT_SECONDS)
!= REDIS_OK) return;
for (j = 1; j < c->argc-1; j++) {
o = lookupKeyWrite(c->db,c->argv[j]);
if (o != NULL) {
if (o->type != REDIS_LIST) {
addReply(c,shared.wrongtypeerr);
return;
} else {
if (listTypeLength(o) != 0) {
/* Non empty list, this is like a non normal [LR]POP. */
char *event = (where == REDIS_HEAD) ? "lpop" : "rpop";
robj *value = listTypePop(o,where);
redisAssert(value != NULL);
addReplyMultiBulkLen(c,2);
addReplyBulk(c,c->argv[j]);
addReplyBulk(c,value);
decrRefCount(value);
notifyKeyspaceEvent(REDIS_NOTIFY_LIST,event,
c->argv[j],c->db->id);
if (listTypeLength(o) == 0) {
dbDelete(c->db,c->argv[j]);
notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",
c->argv[j],c->db->id);
}
signalModifiedKey(c->db,c->argv[j]);
server.dirty++;
/* Replicate it as an [LR]POP instead of B[LR]POP. */
rewriteClientCommandVector(c,2,
(where == REDIS_HEAD) ? shared.lpop : shared.rpop,
c->argv[j]);
return;
}
}
}
}
/* 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 & REDIS_MULTI) {
addReply(c,shared.nullmultibulk);
return;
}
/* If the list is empty or the key does not exists we must block */
blockForKeys(c, c->argv + 1, c->argc - 2, timeout, NULL);
}
void blpopCommand(redisClient *c) {
blockingPopGenericCommand(c,REDIS_HEAD);
}
void brpopCommand(redisClient *c) {
blockingPopGenericCommand(c,REDIS_TAIL);
}
void brpoplpushCommand(redisClient *c) {
mstime_t timeout;
if (getTimeoutFromObjectOrReply(c,c->argv[3],&timeout,UNIT_SECONDS)
!= REDIS_OK) return;
robj *key = lookupKeyWrite(c->db, c->argv[1]);
if (key == NULL) {
if (c->flags & REDIS_MULTI) {
/* Blocking against an empty list in a multi state
* returns immediately. */
addReply(c, shared.nullbulk);
} else {
/* The list is empty and the client blocks. */
blockForKeys(c, c->argv + 1, 1, timeout, c->argv[2]);
}
} else {
if (key->type != REDIS_LIST) {
addReply(c, shared.wrongtypeerr);
} else {
/* The list exists and has elements, so
* the regular rpoplpushCommand is executed. */
redisAssertWithInfo(c,key,listTypeLength(key) > 0);
rpoplpushCommand(c);
}
}
}
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