futriix/src/dict.h

228 lines
8.8 KiB
C
Raw Normal View History

2009-03-22 10:30:00 +01:00
/* Hash Tables Implementation.
*
2012-10-02 21:58:36 -07:00
* This file implements in-memory hash tables with insert/del/replace/find/
* get-random-element operations. Hash tables will auto-resize if needed
2009-03-22 10:30:00 +01:00
* tables of power of two in size are used, collisions are handled by
* chaining. See the source code for more information... :)
*
2012-10-02 21:58:36 -07:00
* Copyright (c) 2006-2012, Salvatore Sanfilippo <antirez at gmail dot com>
2009-03-22 10:30:00 +01:00
* 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.
*/
#ifndef __DICT_H
#define __DICT_H
#include "mt19937-64.h"
#include <limits.h>
#include <stdint.h>
#include <stdlib.h>
2009-03-22 10:30:00 +01:00
#define DICT_OK 0
#define DICT_ERR 1
typedef struct dictEntry {
void *key;
union {
void *val;
uint64_t u64;
int64_t s64;
double d;
} v;
struct dictEntry *next; /* Next entry in the same hash bucket. */
void *metadata[]; /* An arbitrary number of bytes (starting at a
* pointer-aligned address) of size as returned
* by dictType's dictEntryMetadataBytes(). */
2009-03-22 10:30:00 +01:00
} dictEntry;
typedef struct dict dict;
2009-03-22 10:30:00 +01:00
typedef struct dictType {
Use SipHash hash function to mitigate HashDos attempts. This change attempts to switch to an hash function which mitigates the effects of the HashDoS attack (denial of service attack trying to force data structures to worst case behavior) while at the same time providing Redis with an hash function that does not expect the input data to be word aligned, a condition no longer true now that sds.c strings have a varialbe length header. Note that it is possible sometimes that even using an hash function for which collisions cannot be generated without knowing the seed, special implementation details or the exposure of the seed in an indirect way (for example the ability to add elements to a Set and check the return in which Redis returns them with SMEMBERS) may make the attacker's life simpler in the process of trying to guess the correct seed, however the next step would be to switch to a log(N) data structure when too many items in a single bucket are detected: this seems like an overkill in the case of Redis. SPEED REGRESION TESTS: In order to verify that switching from MurmurHash to SipHash had no impact on speed, a set of benchmarks involving fast insertion of 5 million of keys were performed. The result shows Redis with SipHash in high pipelining conditions to be about 4% slower compared to using the previous hash function. However this could partially be related to the fact that the current implementation does not attempt to hash whole words at a time but reads single bytes, in order to have an output which is endian-netural and at the same time working on systems where unaligned memory accesses are a problem. Further X86 specific optimizations should be tested, the function may easily get at the same level of MurMurHash2 if a few optimizations are performed.
2017-02-20 16:09:54 +01:00
uint64_t (*hashFunction)(const void *key);
void *(*keyDup)(dict *d, const void *key);
void *(*valDup)(dict *d, const void *obj);
int (*keyCompare)(dict *d, const void *key1, const void *key2);
void (*keyDestructor)(dict *d, void *key);
void (*valDestructor)(dict *d, void *obj);
Limit the main db and expires dictionaries to expand (#7954) As we know, redis may reject user's requests or evict some keys if used memory is over maxmemory. Dictionaries expanding may make things worse, some big dictionaries, such as main db and expires dict, may eat huge memory at once for allocating a new big hash table and be far more than maxmemory after expanding. There are related issues: #4213 #4583 More details, when expand dict in redis, we will allocate a new big ht[1] that generally is double of ht[0], The size of ht[1] will be very big if ht[0] already is big. For db dict, if we have more than 64 million keys, we need to cost 1GB for ht[1] when dict expands. If the sum of used memory and new hash table of dict needed exceeds maxmemory, we shouldn't allow the dict to expand. Because, if we enable keys eviction, we still couldn't add much more keys after eviction and rehashing, what's worse, redis will keep less keys when redis only remains a little memory for storing new hash table instead of users' data. Moreover users can't write data in redis if disable keys eviction. What this commit changed ? Add a new member function expandAllowed for dict type, it provide a way for caller to allow expand or not. We expose two parameters for this function: more memory needed for expanding and dict current load factor, users can implement a function to make a decision by them. For main db dict and expires dict type, these dictionaries may be very big and cost huge memory for expanding, so we implement a judgement function: we can stop dict to expand provisionally if used memory will be over maxmemory after dict expands, but to guarantee the performance of redis, we still allow dict to expand if dict load factor exceeds the safe load factor. Add test cases to verify we don't allow main db to expand when left memory is not enough, so that avoid keys eviction. Other changes: For new hash table size when expand. Before this commit, the size is that double used of dict and later _dictNextPower. Actually we aim to control a dict load factor between 0.5 and 1.0. Now we replace *2 with +1, since the first check is that used >= size, the outcome of before will usually be the same as _dictNextPower(used+1). The only case where it'll differ is when dict_can_resize is false during fork, so that later the _dictNextPower(used*2) will cause the dict to jump to *4 (i.e. _dictNextPower(1025*2) will return 4096). Fix rehash test cases due to changing algorithm of new hash table size when expand.
2020-12-06 17:53:04 +08:00
int (*expandAllowed)(size_t moreMem, double usedRatio);
/* Allow a dictEntry to carry extra caller-defined metadata. The
* extra memory is initialized to 0 when a dictEntry is allocated. */
size_t (*dictEntryMetadataBytes)(dict *d);
2009-03-22 10:30:00 +01:00
} dictType;
#define DICTHT_SIZE(exp) ((exp) == -1 ? 0 : (unsigned long)1<<(exp))
#define DICTHT_SIZE_MASK(exp) ((exp) == -1 ? 0 : (DICTHT_SIZE(exp))-1)
struct dict {
dictType *type;
dictEntry **ht_table[2];
unsigned long ht_used[2];
long rehashidx; /* rehashing not in progress if rehashidx == -1 */
/* Keep small vars at end for optimal (minimal) struct padding */
int16_t pauserehash; /* If >0 rehashing is paused (<0 indicates coding error) */
signed char ht_size_exp[2]; /* exponent of size. (size = 1<<exp) */
};
2009-03-22 10:30:00 +01:00
2012-10-02 21:58:36 -07:00
/* If safe is set to 1 this is a safe iterator, that means, you can call
* dictAdd, dictFind, and other functions against the dictionary even while
* iterating. Otherwise it is a non safe iterator, and only dictNext()
* should be called while iterating. */
2009-03-22 10:30:00 +01:00
typedef struct dictIterator {
dict *d;
long index;
int table, safe;
2009-03-22 10:30:00 +01:00
dictEntry *entry, *nextEntry;
/* unsafe iterator fingerprint for misuse detection. */
unsigned long long fingerprint;
2009-03-22 10:30:00 +01:00
} dictIterator;
2012-07-09 01:00:26 -07:00
typedef void (dictScanFunction)(void *privdata, const dictEntry *de);
typedef void (dictScanBucketFunction)(dict *d, dictEntry **bucketref);
2012-07-09 01:00:26 -07:00
2009-03-22 10:30:00 +01:00
/* This is the initial size of every hash table */
#define DICT_HT_INITIAL_EXP 2
#define DICT_HT_INITIAL_SIZE (1<<(DICT_HT_INITIAL_EXP))
2009-03-22 10:30:00 +01:00
/* ------------------------------- Macros ------------------------------------*/
#define dictFreeVal(d, entry) do { \
if ((d)->type->valDestructor) \
(d)->type->valDestructor((d), (entry)->v.val); \
} while(0)
2009-03-22 10:30:00 +01:00
#define dictSetVal(d, entry, _val_) do { \
if ((d)->type->valDup) \
(entry)->v.val = (d)->type->valDup((d), _val_); \
2009-03-22 10:30:00 +01:00
else \
(entry)->v.val = (_val_); \
2009-03-22 10:30:00 +01:00
} while(0)
#define dictSetSignedIntegerVal(entry, _val_) \
do { (entry)->v.s64 = _val_; } while(0)
#define dictSetUnsignedIntegerVal(entry, _val_) \
do { (entry)->v.u64 = _val_; } while(0)
#define dictSetDoubleVal(entry, _val_) \
do { (entry)->v.d = _val_; } while(0)
reprocess command when client is unblocked on keys (#11012) *TL;DR* --------------------------------------- Following the discussion over the issue [#7551](https://github.com/redis/redis/issues/7551) We decided to refactor the client blocking code to eliminate some of the code duplications and to rebuild the infrastructure better for future key blocking cases. *In this PR* --------------------------------------- 1. reprocess the command once a client becomes unblocked on key (instead of running custom code for the unblocked path that's different than the one that would have run if blocking wasn't needed) 2. eliminate some (now) irrelevant code for handling unblocking lists/zsets/streams etc... 3. modify some tests to intercept the error in cases of error on reprocess after unblock (see details in the notes section below) 4. replace '$' on the client argv with current stream id. Since once we reprocess the stream XREAD we need to read from the last msg and not wait for new msg in order to prevent endless block loop. 5. Added statistics to the info "Clients" section to report the: * `total_blocking_keys` - number of blocking keys * `total_blocking_keys_on_nokey` - number of blocking keys which have at least 1 client which would like to be unblocked on when the key is deleted. 6. Avoid expiring unblocked key during unblock. Previously we used to lookup the unblocked key which might have been expired during the lookup. Now we lookup the key using NOTOUCH and NOEXPIRE to avoid deleting it at this point, so propagating commands in blocked.c is no longer needed. 7. deprecated command flags. We decided to remove the CMD_CALL_STATS and CMD_CALL_SLOWLOG and make an explicit verification in the call() function in order to decide if stats update should take place. This should simplify the logic and also mitigate existing issues: for example module calls which are triggered as part of AOF loading might still report stats even though they are called during AOF loading. *Behavior changes* --------------------------------------------------- 1. As this implementation prevents writing dedicated code handling unblocked streams/lists/zsets, since we now re-process the command once the client is unblocked some errors will be reported differently. The old implementation used to issue ``UNBLOCKED the stream key no longer exists`` in the following cases: - The stream key has been deleted (ie. calling DEL) - The stream and group existed but the key type was changed by overriding it (ie. with set command) - The key not longer exists after we swapdb with a db which does not contains this key - After swapdb when the new db has this key but with different type. In the new implementation the reported errors will be the same as if the command was processed after effect: **NOGROUP** - in case key no longer exists, or **WRONGTYPE** in case the key was overridden with a different type. 2. Reprocessing the command means that some checks will be reevaluated once the client is unblocked. For example, ACL rules might change since the command originally was executed and will fail once the client is unblocked. Another example is OOM condition checks which might enable the command to run and block but fail the command reprocess once the client is unblocked. 3. One of the changes in this PR is that no command stats are being updated once the command is blocked (all stats will be updated once the client is unblocked). This implies that when we have many clients blocked, users will no longer be able to get that information from the command stats. However the information can still be gathered from the client list. **Client blocking** --------------------------------------------------- the blocking on key will still be triggered the same way as it is done today. in order to block the current client on list of keys, the call to blockForKeys will still need to be made which will perform the same as it is today: * add the client to the list of blocked clients on each key * keep the key with a matching list node (position in the global blocking clients list for that key) in the client private blocking key dict. * flag the client with CLIENT_BLOCKED * update blocking statistics * register the client on the timeout table **Key Unblock** --------------------------------------------------- Unblocking a specific key will be triggered (same as today) by calling signalKeyAsReady. the implementation in that part will stay the same as today - adding the key to the global readyList. The reason to maintain the readyList (as apposed to iterating over all clients blocked on the specific key) is in order to keep the signal operation as short as possible, since it is called during the command processing. The main change is that instead of going through a dedicated code path that operates the blocked command we will just call processPendingCommandsAndResetClient. **ClientUnblock (keys)** --------------------------------------------------- 1. Unblocking clients on keys will be triggered after command is processed and during the beforeSleep 8. the general schema is: 9. For each key *k* in the readyList: ``` For each client *c* which is blocked on *k*: in case either: 1. *k* exists AND the *k* type matches the current client blocking type OR 2. *k* exists and *c* is blocked on module command OR 3. *k* does not exists and *c* was blocked with the flag unblock_on_deleted_key do: 1. remove the client from the list of clients blocked on this key 2. remove the blocking list node from the client blocking key dict 3. remove the client from the timeout list 10. queue the client on the unblocked_clients list 11. *NEW*: call processCommandAndResetClient(c); ``` *NOTE:* for module blocked clients we will still call the moduleUnblockClientByHandle which will queue the client for processing in moduleUnblockedClients list. **Process Unblocked clients** --------------------------------------------------- The process of all unblocked clients is done in the beforeSleep and no change is planned in that part. The general schema will be: For each client *c* in server.unblocked_clients: * remove client from the server.unblocked_clients * set back the client readHandler * continue processing the pending command and input buffer. *Some notes regarding the new implementation* --------------------------------------------------- 1. Although it was proposed, it is currently difficult to remove the read handler from the client while it is blocked. The reason is that a blocked client should be unblocked when it is disconnected, or we might consume data into void. 2. While this PR mainly keep the current blocking logic as-is, there might be some future additions to the infrastructure that we would like to have: - allow non-preemptive blocking of client - sometimes we can think that a new kind of blocking can be expected to not be preempt. for example lets imagine we hold some keys on disk and when a command needs to process them it will block until the keys are uploaded. in this case we will want the client to not disconnect or be unblocked until the process is completed (remove the client read handler, prevent client timeout, disable unblock via debug command etc...). - allow generic blocking based on command declared keys - we might want to add a hook before command processing to check if any of the declared keys require the command to block. this way it would be easier to add new kinds of key-based blocking mechanisms. Co-authored-by: Oran Agra <oran@redislabs.com> Signed-off-by: Ran Shidlansik <ranshid@amazon.com>
2023-01-01 23:35:42 +02:00
#define dictIncrSignedIntegerVal(entry, _val_) \
((entry)->v.s64 += _val_)
#define dictIncrUnsignedIntegerVal(entry, _val_) \
((entry)->v.u64 += _val_)
#define dictIncrDoubleVal(entry, _val_) \
((entry)->v.d += _val_)
#define dictFreeKey(d, entry) \
if ((d)->type->keyDestructor) \
(d)->type->keyDestructor((d), (entry)->key)
2009-03-22 10:30:00 +01:00
#define dictSetKey(d, entry, _key_) do { \
if ((d)->type->keyDup) \
(entry)->key = (d)->type->keyDup((d), _key_); \
2009-03-22 10:30:00 +01:00
else \
(entry)->key = (_key_); \
2009-03-22 10:30:00 +01:00
} while(0)
#define dictCompareKeys(d, key1, key2) \
(((d)->type->keyCompare) ? \
(d)->type->keyCompare((d), key1, key2) : \
2009-03-22 10:30:00 +01:00
(key1) == (key2))
#define dictMetadata(entry) (&(entry)->metadata)
#define dictMetadataSize(d) ((d)->type->dictEntryMetadataBytes \
? (d)->type->dictEntryMetadataBytes(d) : 0)
#define dictHashKey(d, key) ((d)->type->hashFunction(key))
#define dictGetKey(he) ((he)->key)
#define dictGetVal(he) ((he)->v.val)
#define dictGetSignedIntegerVal(he) ((he)->v.s64)
#define dictGetUnsignedIntegerVal(he) ((he)->v.u64)
#define dictGetDoubleVal(he) ((he)->v.d)
#define dictSlots(d) (DICTHT_SIZE((d)->ht_size_exp[0])+DICTHT_SIZE((d)->ht_size_exp[1]))
#define dictSize(d) ((d)->ht_used[0]+(d)->ht_used[1])
#define dictIsRehashing(d) ((d)->rehashidx != -1)
#define dictPauseRehashing(d) ((d)->pauserehash++)
#define dictResumeRehashing(d) ((d)->pauserehash--)
2009-03-22 10:30:00 +01:00
/* If our unsigned long type can store a 64 bit number, use a 64 bit PRNG. */
#if ULONG_MAX >= 0xffffffffffffffff
#define randomULong() ((unsigned long) genrand64_int64())
#else
#define randomULong() random()
#endif
2009-03-22 10:30:00 +01:00
/* API */
dict *dictCreate(dictType *type);
2010-04-15 18:07:57 +02:00
int dictExpand(dict *d, unsigned long size);
int dictTryExpand(dict *d, unsigned long size);
2010-04-15 18:07:57 +02:00
int dictAdd(dict *d, void *key, void *val);
dictEntry *dictAddRaw(dict *d, void *key, dictEntry **existing);
dictEntry *dictAddOrFind(dict *d, void *key);
2010-04-15 18:07:57 +02:00
int dictReplace(dict *d, void *key, void *val);
int dictDelete(dict *d, const void *key);
dictEntry *dictUnlink(dict *d, const void *key);
void dictFreeUnlinkedEntry(dict *d, dictEntry *he);
Add a special notification unlink available only for modules (#9406) Add a new module event `RedisModule_Event_Key`, this event is fired when a key is removed from the keyspace. The event includes an open key that can be used for reading the key before it is removed. Modules can also extract the key-name, and use RM_Open or RM_Call to access key from within that event, but shouldn't modify anything from within this event. The following sub events are available: - `REDISMODULE_SUBEVENT_KEY_DELETED` - `REDISMODULE_SUBEVENT_KEY_EXPIRED` - `REDISMODULE_SUBEVENT_KEY_EVICTED` - `REDISMODULE_SUBEVENT_KEY_OVERWRITE` The data pointer can be casted to a RedisModuleKeyInfo structure with the following fields: ``` RedisModuleKey *key; // Opened Key ``` ### internals * We also add two dict functions: `dictTwoPhaseUnlinkFind` finds an element from the table, also get the plink of the entry. The entry is returned if the element is found. The user should later call `dictTwoPhaseUnlinkFree` with it in order to unlink and release it. Otherwise if the key is not found, NULL is returned. These two functions should be used in pair. `dictTwoPhaseUnlinkFind` pauses rehash and `dictTwoPhaseUnlinkFree` resumes rehash. * We change `dbOverwrite` to `dbReplaceValue` which just replaces the value of the key and doesn't fire any events. The "overwrite" part (which emits events) is just when called from `setKey`, the other places that called dbOverwrite were ones that just update the value in-place (INCR*, SPOP, and dbUnshareStringValue). This should not have any real impact since `moduleNotifyKeyUnlink` and `signalDeletedKeyAsReady` wouldn't have mattered in these cases anyway (i.e. module keys and stream keys didn't have direct calls to dbOverwrite) * since we allow doing RM_OpenKey from withing these callbacks, we temporarily disable lazy expiry. * We also temporarily disable lazy expiry when we are in unlink/unlink2 callback and keyspace notification callback. * Move special definitions to the top of redismodule.h This is needed to resolve compilation errors with RedisModuleKeyInfoV1 that carries a RedisModuleKey member. Co-authored-by: Oran Agra <oran@redislabs.com>
2022-11-30 17:56:36 +08:00
dictEntry *dictTwoPhaseUnlinkFind(dict *d, const void *key, dictEntry ***plink, int *table_index);
void dictTwoPhaseUnlinkFree(dict *d, dictEntry *he, dictEntry **plink, int table_index);
2010-04-15 18:07:57 +02:00
void dictRelease(dict *d);
dictEntry * dictFind(dict *d, const void *key);
void *dictFetchValue(dict *d, const void *key);
2010-04-15 18:07:57 +02:00
int dictResize(dict *d);
dictIterator *dictGetIterator(dict *d);
dictIterator *dictGetSafeIterator(dict *d);
void dictInitIterator(dictIterator *iter, dict *d);
void dictInitSafeIterator(dictIterator *iter, dict *d);
void dictResetIterator(dictIterator *iter);
2009-03-22 10:30:00 +01:00
dictEntry *dictNext(dictIterator *iter);
void dictReleaseIterator(dictIterator *iter);
2010-04-15 18:07:57 +02:00
dictEntry *dictGetRandomKey(dict *d);
dictEntry *dictGetFairRandomKey(dict *d);
unsigned int dictGetSomeKeys(dict *d, dictEntry **des, unsigned int count);
void dictGetStats(char *buf, size_t bufsize, dict *d);
uint64_t dictGenHashFunction(const void *key, size_t len);
uint64_t dictGenCaseHashFunction(const unsigned char *buf, size_t len);
void dictEmpty(dict *d, void(callback)(dict*));
void dictEnableResize(void);
void dictDisableResize(void);
int dictRehash(dict *d, int n);
2010-04-15 18:07:57 +02:00
int dictRehashMilliseconds(dict *d, int ms);
Use SipHash hash function to mitigate HashDos attempts. This change attempts to switch to an hash function which mitigates the effects of the HashDoS attack (denial of service attack trying to force data structures to worst case behavior) while at the same time providing Redis with an hash function that does not expect the input data to be word aligned, a condition no longer true now that sds.c strings have a varialbe length header. Note that it is possible sometimes that even using an hash function for which collisions cannot be generated without knowing the seed, special implementation details or the exposure of the seed in an indirect way (for example the ability to add elements to a Set and check the return in which Redis returns them with SMEMBERS) may make the attacker's life simpler in the process of trying to guess the correct seed, however the next step would be to switch to a log(N) data structure when too many items in a single bucket are detected: this seems like an overkill in the case of Redis. SPEED REGRESION TESTS: In order to verify that switching from MurmurHash to SipHash had no impact on speed, a set of benchmarks involving fast insertion of 5 million of keys were performed. The result shows Redis with SipHash in high pipelining conditions to be about 4% slower compared to using the previous hash function. However this could partially be related to the fact that the current implementation does not attempt to hash whole words at a time but reads single bytes, in order to have an output which is endian-netural and at the same time working on systems where unaligned memory accesses are a problem. Further X86 specific optimizations should be tested, the function may easily get at the same level of MurMurHash2 if a few optimizations are performed.
2017-02-20 16:09:54 +01:00
void dictSetHashFunctionSeed(uint8_t *seed);
uint8_t *dictGetHashFunctionSeed(void);
2016-12-30 03:37:52 +02:00
unsigned long dictScan(dict *d, unsigned long v, dictScanFunction *fn, dictScanBucketFunction *bucketfn, void *privdata);
2017-11-30 11:34:37 +08:00
uint64_t dictGetHash(dict *d, const void *key);
dictEntry **dictFindEntryRefByPtrAndHash(dict *d, const void *oldptr, uint64_t hash);
2009-03-22 10:30:00 +01:00
#ifdef REDIS_TEST
int dictTest(int argc, char *argv[], int flags);
#endif
2009-03-22 10:30:00 +01:00
#endif /* __DICT_H */