Adding upstream version 5:7.0.15.upstream/5%7.0.15upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 764 insertions, 0 deletions

diff --git a/src/expire.c b/src/expire.c
new file mode 100644
index 0000000..a57bcf2
--- /dev/null
+++ b/src/expire.c
@@ -0,0 +1,764 @@
+/* Implementation of EXPIRE (keys with fixed time to live).
+ *
+ * ----------------------------------------------------------------------------
+ *
+ * Copyright (c) 2009-2016, 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"
+
+/*-----------------------------------------------------------------------------
+ * Incremental collection of expired keys.
+ *
+ * When keys are accessed they are expired on-access. However we need a
+ * mechanism in order to ensure keys are eventually removed when expired even
+ * if no access is performed on them.
+ *----------------------------------------------------------------------------*/
+
+/* Helper function for the activeExpireCycle() function.
+ * This function will try to expire the key that is stored in the hash table
+ * entry 'de' of the 'expires' hash table of a Redis database.
+ *
+ * If the key is found to be expired, it is removed from the database and
+ * 1 is returned. Otherwise no operation is performed and 0 is returned.
+ *
+ * When a key is expired, server.stat_expiredkeys is incremented.
+ *
+ * The parameter 'now' is the current time in milliseconds as is passed
+ * to the function to avoid too many gettimeofday() syscalls. */
+int activeExpireCycleTryExpire(redisDb *db, dictEntry *de, long long now) {
+    long long t = dictGetSignedIntegerVal(de);
+    if (now > t) {
+        sds key = dictGetKey(de);
+        robj *keyobj = createStringObject(key,sdslen(key));
+        deleteExpiredKeyAndPropagate(db,keyobj);
+        decrRefCount(keyobj);
+        return 1;
+    } else {
+        return 0;
+    }
+}
+
+/* Try to expire a few timed out keys. The algorithm used is adaptive and
+ * will use few CPU cycles if there are few expiring keys, otherwise
+ * it will get more aggressive to avoid that too much memory is used by
+ * keys that can be removed from the keyspace.
+ *
+ * Every expire cycle tests multiple databases: the next call will start
+ * again from the next db. No more than CRON_DBS_PER_CALL databases are
+ * tested at every iteration.
+ *
+ * The function can perform more or less work, depending on the "type"
+ * argument. It can execute a "fast cycle" or a "slow cycle". The slow
+ * cycle is the main way we collect expired cycles: this happens with
+ * the "server.hz" frequency (usually 10 hertz).
+ *
+ * However the slow cycle can exit for timeout, since it used too much time.
+ * For this reason the function is also invoked to perform a fast cycle
+ * at every event loop cycle, in the beforeSleep() function. The fast cycle
+ * will try to perform less work, but will do it much more often.
+ *
+ * The following are the details of the two expire cycles and their stop
+ * conditions:
+ *
+ * If type is ACTIVE_EXPIRE_CYCLE_FAST the function will try to run a
+ * "fast" expire cycle that takes no longer than ACTIVE_EXPIRE_CYCLE_FAST_DURATION
+ * microseconds, and is not repeated again before the same amount of time.
+ * The cycle will also refuse to run at all if the latest slow cycle did not
+ * terminate because of a time limit condition.
+ *
+ * If type is ACTIVE_EXPIRE_CYCLE_SLOW, that normal expire cycle is
+ * executed, where the time limit is a percentage of the REDIS_HZ period
+ * as specified by the ACTIVE_EXPIRE_CYCLE_SLOW_TIME_PERC define. In the
+ * fast cycle, the check of every database is interrupted once the number
+ * of already expired keys in the database is estimated to be lower than
+ * a given percentage, in order to avoid doing too much work to gain too
+ * little memory.
+ *
+ * The configured expire "effort" will modify the baseline parameters in
+ * order to do more work in both the fast and slow expire cycles.
+ */
+
+#define ACTIVE_EXPIRE_CYCLE_KEYS_PER_LOOP 20 /* Keys for each DB loop. */
+#define ACTIVE_EXPIRE_CYCLE_FAST_DURATION 1000 /* Microseconds. */
+#define ACTIVE_EXPIRE_CYCLE_SLOW_TIME_PERC 25 /* Max % of CPU to use. */
+#define ACTIVE_EXPIRE_CYCLE_ACCEPTABLE_STALE 10 /* % of stale keys after which
+                                                   we do extra efforts. */
+
+void activeExpireCycle(int type) {
+    /* Adjust the running parameters according to the configured expire
+     * effort. The default effort is 1, and the maximum configurable effort
+     * is 10. */
+    unsigned long
+    effort = server.active_expire_effort-1, /* Rescale from 0 to 9. */
+    config_keys_per_loop = ACTIVE_EXPIRE_CYCLE_KEYS_PER_LOOP +
+                           ACTIVE_EXPIRE_CYCLE_KEYS_PER_LOOP/4*effort,
+    config_cycle_fast_duration = ACTIVE_EXPIRE_CYCLE_FAST_DURATION +
+                                 ACTIVE_EXPIRE_CYCLE_FAST_DURATION/4*effort,
+    config_cycle_slow_time_perc = ACTIVE_EXPIRE_CYCLE_SLOW_TIME_PERC +
+                                  2*effort,
+    config_cycle_acceptable_stale = ACTIVE_EXPIRE_CYCLE_ACCEPTABLE_STALE-
+                                    effort;
+
+    /* This function has some global state in order to continue the work
+     * incrementally across calls. */
+    static unsigned int current_db = 0; /* Next DB to test. */
+    static int timelimit_exit = 0;      /* Time limit hit in previous call? */
+    static long long last_fast_cycle = 0; /* When last fast cycle ran. */
+
+    int j, iteration = 0;
+    int dbs_per_call = CRON_DBS_PER_CALL;
+    long long start = ustime(), timelimit, elapsed;
+
+    /* When clients are paused the dataset should be static not just from the
+     * POV of clients not being able to write, but also from the POV of
+     * expires and evictions of keys not being performed. */
+    if (checkClientPauseTimeoutAndReturnIfPaused()) return;
+
+    if (type == ACTIVE_EXPIRE_CYCLE_FAST) {
+        /* Don't start a fast cycle if the previous cycle did not exit
+         * for time limit, unless the percentage of estimated stale keys is
+         * too high. Also never repeat a fast cycle for the same period
+         * as the fast cycle total duration itself. */
+        if (!timelimit_exit &&
+            server.stat_expired_stale_perc < config_cycle_acceptable_stale)
+            return;
+
+        if (start < last_fast_cycle + (long long)config_cycle_fast_duration*2)
+            return;
+
+        last_fast_cycle = start;
+    }
+
+    /* We usually should test CRON_DBS_PER_CALL per iteration, with
+     * two exceptions:
+     *
+     * 1) Don't test more DBs than we have.
+     * 2) If last time we hit the time limit, we want to scan all DBs
+     * in this iteration, as there is work to do in some DB and we don't want
+     * expired keys to use memory for too much time. */
+    if (dbs_per_call > server.dbnum || timelimit_exit)
+        dbs_per_call = server.dbnum;
+
+    /* We can use at max 'config_cycle_slow_time_perc' percentage of CPU
+     * time per iteration. Since this function gets called with a frequency of
+     * server.hz times per second, the following is the max amount of
+     * microseconds we can spend in this function. */
+    timelimit = config_cycle_slow_time_perc*1000000/server.hz/100;
+    timelimit_exit = 0;
+    if (timelimit <= 0) timelimit = 1;
+
+    if (type == ACTIVE_EXPIRE_CYCLE_FAST)
+        timelimit = config_cycle_fast_duration; /* in microseconds. */
+
+    /* Accumulate some global stats as we expire keys, to have some idea
+     * about the number of keys that are already logically expired, but still
+     * existing inside the database. */
+    long total_sampled = 0;
+    long total_expired = 0;
+
+    /* Sanity: There can't be any pending commands to propagate when
+     * we're in cron */
+    serverAssert(server.also_propagate.numops == 0);
+    server.core_propagates = 1;
+    server.propagate_no_multi = 1;
+
+    for (j = 0; j < dbs_per_call && timelimit_exit == 0; j++) {
+        /* Expired and checked in a single loop. */
+        unsigned long expired, sampled;
+
+        redisDb *db = server.db+(current_db % server.dbnum);
+
+        /* Increment the DB now so we are sure if we run out of time
+         * in the current DB we'll restart from the next. This allows to
+         * distribute the time evenly across DBs. */
+        current_db++;
+
+        /* Continue to expire if at the end of the cycle there are still
+         * a big percentage of keys to expire, compared to the number of keys
+         * we scanned. The percentage, stored in config_cycle_acceptable_stale
+         * is not fixed, but depends on the Redis configured "expire effort". */
+        do {
+            unsigned long num, slots;
+            long long now, ttl_sum;
+            int ttl_samples;
+            iteration++;
+
+            /* If there is nothing to expire try next DB ASAP. */
+            if ((num = dictSize(db->expires)) == 0) {
+                db->avg_ttl = 0;
+                break;
+            }
+            slots = dictSlots(db->expires);
+            now = mstime();
+
+            /* When there are less than 1% filled slots, sampling the key
+             * space is expensive, so stop here waiting for better times...
+             * The dictionary will be resized asap. */
+            if (slots > DICT_HT_INITIAL_SIZE &&
+                (num*100/slots < 1)) break;
+
+            /* The main collection cycle. Sample random keys among keys
+             * with an expire set, checking for expired ones. */
+            expired = 0;
+            sampled = 0;
+            ttl_sum = 0;
+            ttl_samples = 0;
+
+            if (num > config_keys_per_loop)
+                num = config_keys_per_loop;
+
+            /* Here we access the low level representation of the hash table
+             * for speed concerns: this makes this code coupled with dict.c,
+             * but it hardly changed in ten years.
+             *
+             * Note that certain places of the hash table may be empty,
+             * so we want also a stop condition about the number of
+             * buckets that we scanned. However scanning for free buckets
+             * is very fast: we are in the cache line scanning a sequential
+             * array of NULL pointers, so we can scan a lot more buckets
+             * than keys in the same time. */
+            long max_buckets = num*20;
+            long checked_buckets = 0;
+
+            while (sampled < num && checked_buckets < max_buckets) {
+                for (int table = 0; table < 2; table++) {
+                    if (table == 1 && !dictIsRehashing(db->expires)) break;
+
+                    unsigned long idx = db->expires_cursor;
+                    idx &= DICTHT_SIZE_MASK(db->expires->ht_size_exp[table]);
+                    dictEntry *de = db->expires->ht_table[table][idx];
+                    long long ttl;
+
+                    /* Scan the current bucket of the current table. */
+                    checked_buckets++;
+                    while(de) {
+                        /* Get the next entry now since this entry may get
+                         * deleted. */
+                        dictEntry *e = de;
+                        de = de->next;
+
+                        ttl = dictGetSignedIntegerVal(e)-now;
+                        if (activeExpireCycleTryExpire(db,e,now)) expired++;
+                        if (ttl > 0) {
+                            /* We want the average TTL of keys yet
+                             * not expired. */
+                            ttl_sum += ttl;
+                            ttl_samples++;
+                        }
+                        sampled++;
+                    }
+                }
+                db->expires_cursor++;
+            }
+            total_expired += expired;
+            total_sampled += sampled;
+
+            /* Update the average TTL stats for this database. */
+            if (ttl_samples) {
+                long long avg_ttl = ttl_sum/ttl_samples;
+
+                /* Do a simple running average with a few samples.
+                 * We just use the current estimate with a weight of 2%
+                 * and the previous estimate with a weight of 98%. */
+                if (db->avg_ttl == 0) db->avg_ttl = avg_ttl;
+                db->avg_ttl = (db->avg_ttl/50)*49 + (avg_ttl/50);
+            }
+
+            /* We can't block forever here even if there are many keys to
+             * expire. So after a given amount of milliseconds return to the
+             * caller waiting for the other active expire cycle. */
+            if ((iteration & 0xf) == 0) { /* check once every 16 iterations. */
+                elapsed = ustime()-start;
+                if (elapsed > timelimit) {
+                    timelimit_exit = 1;
+                    server.stat_expired_time_cap_reached_count++;
+                    break;
+                }
+            }
+            /* We don't repeat the cycle for the current database if there are
+             * an acceptable amount of stale keys (logically expired but yet
+             * not reclaimed). */
+        } while (sampled == 0 ||
+                 (expired*100/sampled) > config_cycle_acceptable_stale);
+    }
+
+    serverAssert(server.core_propagates); /* This function should not be re-entrant */
+
+    /* Propagate all DELs */
+    propagatePendingCommands();
+
+    server.core_propagates = 0;
+    server.propagate_no_multi = 0;
+
+    elapsed = ustime()-start;
+    server.stat_expire_cycle_time_used += elapsed;
+    latencyAddSampleIfNeeded("expire-cycle",elapsed/1000);
+
+    /* Update our estimate of keys existing but yet to be expired.
+     * Running average with this sample accounting for 5%. */
+    double current_perc;
+    if (total_sampled) {
+        current_perc = (double)total_expired/total_sampled;
+    } else
+        current_perc = 0;
+    server.stat_expired_stale_perc = (current_perc*0.05)+
+                                     (server.stat_expired_stale_perc*0.95);
+}
+
+/*-----------------------------------------------------------------------------
+ * Expires of keys created in writable slaves
+ *
+ * Normally slaves do not process expires: they wait the masters to synthesize
+ * DEL operations in order to retain consistency. However writable slaves are
+ * an exception: if a key is created in the slave and an expire is assigned
+ * to it, we need a way to expire such a key, since the master does not know
+ * anything about such a key.
+ *
+ * In order to do so, we track keys created in the slave side with an expire
+ * set, and call the expireSlaveKeys() function from time to time in order to
+ * reclaim the keys if they already expired.
+ *
+ * Note that the use case we are trying to cover here, is a popular one where
+ * slaves are put in writable mode in order to compute slow operations in
+ * the slave side that are mostly useful to actually read data in a more
+ * processed way. Think at sets intersections in a tmp key, with an expire so
+ * that it is also used as a cache to avoid intersecting every time.
+ *
+ * This implementation is currently not perfect but a lot better than leaking
+ * the keys as implemented in 3.2.
+ *----------------------------------------------------------------------------*/
+
+/* The dictionary where we remember key names and database ID of keys we may
+ * want to expire from the slave. Since this function is not often used we
+ * don't even care to initialize the database at startup. We'll do it once
+ * the feature is used the first time, that is, when rememberSlaveKeyWithExpire()
+ * is called.
+ *
+ * The dictionary has an SDS string representing the key as the hash table
+ * key, while the value is a 64 bit unsigned integer with the bits corresponding
+ * to the DB where the keys may exist set to 1. Currently the keys created
+ * with a DB id > 63 are not expired, but a trivial fix is to set the bitmap
+ * to the max 64 bit unsigned value when we know there is a key with a DB
+ * ID greater than 63, and check all the configured DBs in such a case. */
+dict *slaveKeysWithExpire = NULL;
+
+/* Check the set of keys created by the master with an expire set in order to
+ * check if they should be evicted. */
+void expireSlaveKeys(void) {
+    if (slaveKeysWithExpire == NULL ||
+        dictSize(slaveKeysWithExpire) == 0) return;
+
+    int cycles = 0, noexpire = 0;
+    mstime_t start = mstime();
+    while(1) {
+        dictEntry *de = dictGetRandomKey(slaveKeysWithExpire);
+        sds keyname = dictGetKey(de);
+        uint64_t dbids = dictGetUnsignedIntegerVal(de);
+        uint64_t new_dbids = 0;
+
+        /* Check the key against every database corresponding to the
+         * bits set in the value bitmap. */
+        int dbid = 0;
+        while(dbids && dbid < server.dbnum) {
+            if ((dbids & 1) != 0) {
+                redisDb *db = server.db+dbid;
+                dictEntry *expire = dictFind(db->expires,keyname);
+                int expired = 0;
+
+                if (expire &&
+                    activeExpireCycleTryExpire(server.db+dbid,expire,start))
+                {
+                    expired = 1;
+                }
+
+                /* If the key was not expired in this DB, we need to set the
+                 * corresponding bit in the new bitmap we set as value.
+                 * At the end of the loop if the bitmap is zero, it means we
+                 * no longer need to keep track of this key. */
+                if (expire && !expired) {
+                    noexpire++;
+                    new_dbids |= (uint64_t)1 << dbid;
+                }
+            }
+            dbid++;
+            dbids >>= 1;
+        }
+
+        /* Set the new bitmap as value of the key, in the dictionary
+         * of keys with an expire set directly in the writable slave. Otherwise
+         * if the bitmap is zero, we no longer need to keep track of it. */
+        if (new_dbids)
+            dictSetUnsignedIntegerVal(de,new_dbids);
+        else
+            dictDelete(slaveKeysWithExpire,keyname);
+
+        /* Stop conditions: found 3 keys we can't expire in a row or
+         * time limit was reached. */
+        cycles++;
+        if (noexpire > 3) break;
+        if ((cycles % 64) == 0 && mstime()-start > 1) break;
+        if (dictSize(slaveKeysWithExpire) == 0) break;
+    }
+
+    /* Propagate the DEL (writable replicas do not propagate anything to other replicas,
+     * but they might propagate to AOF) and trigger module hooks. */
+    propagatePendingCommands();
+}
+
+/* Track keys that received an EXPIRE or similar command in the context
+ * of a writable slave. */
+void rememberSlaveKeyWithExpire(redisDb *db, robj *key) {
+    if (slaveKeysWithExpire == NULL) {
+        static dictType dt = {
+            dictSdsHash,                /* hash function */
+            NULL,                       /* key dup */
+            NULL,                       /* val dup */
+            dictSdsKeyCompare,          /* key compare */
+            dictSdsDestructor,          /* key destructor */
+            NULL,                       /* val destructor */
+            NULL                        /* allow to expand */
+        };
+        slaveKeysWithExpire = dictCreate(&dt);
+    }
+    if (db->id > 63) return;
+
+    dictEntry *de = dictAddOrFind(slaveKeysWithExpire,key->ptr);
+    /* If the entry was just created, set it to a copy of the SDS string
+     * representing the key: we don't want to need to take those keys
+     * in sync with the main DB. The keys will be removed by expireSlaveKeys()
+     * as it scans to find keys to remove. */
+    if (de->key == key->ptr) {
+        de->key = sdsdup(key->ptr);
+        dictSetUnsignedIntegerVal(de,0);
+    }
+
+    uint64_t dbids = dictGetUnsignedIntegerVal(de);
+    dbids |= (uint64_t)1 << db->id;
+    dictSetUnsignedIntegerVal(de,dbids);
+}
+
+/* Return the number of keys we are tracking. */
+size_t getSlaveKeyWithExpireCount(void) {
+    if (slaveKeysWithExpire == NULL) return 0;
+    return dictSize(slaveKeysWithExpire);
+}
+
+/* Remove the keys in the hash table. We need to do that when data is
+ * flushed from the server. We may receive new keys from the master with
+ * the same name/db and it is no longer a good idea to expire them.
+ *
+ * Note: technically we should handle the case of a single DB being flushed
+ * but it is not worth it since anyway race conditions using the same set
+ * of key names in a writable slave and in its master will lead to
+ * inconsistencies. This is just a best-effort thing we do. */
+void flushSlaveKeysWithExpireList(void) {
+    if (slaveKeysWithExpire) {
+        dictRelease(slaveKeysWithExpire);
+        slaveKeysWithExpire = NULL;
+    }
+}
+
+int checkAlreadyExpired(long long when) {
+    /* EXPIRE with negative TTL, or EXPIREAT with a timestamp into the past
+     * should never be executed as a DEL when load the AOF or in the context
+     * of a slave instance.
+     *
+     * Instead we add the already expired key to the database with expire time
+     * (possibly in the past) and wait for an explicit DEL from the master. */
+    return (when <= mstime() && !server.loading && !server.masterhost);
+}
+
+#define EXPIRE_NX (1<<0)
+#define EXPIRE_XX (1<<1)
+#define EXPIRE_GT (1<<2)
+#define EXPIRE_LT (1<<3)
+
+/* Parse additional flags of expire commands
+ *
+ * Supported flags:
+ * - NX: set expiry only when the key has no expiry
+ * - XX: set expiry only when the key has an existing expiry
+ * - GT: set expiry only when the new expiry is greater than current one
+ * - LT: set expiry only when the new expiry is less than current one */
+int parseExtendedExpireArgumentsOrReply(client *c, int *flags) {
+    int nx = 0, xx = 0, gt = 0, lt = 0;
+
+    int j = 3;
+    while (j < c->argc) {
+        char *opt = c->argv[j]->ptr;
+        if (!strcasecmp(opt,"nx")) {
+            *flags |= EXPIRE_NX;
+            nx = 1;
+        } else if (!strcasecmp(opt,"xx")) {
+            *flags |= EXPIRE_XX;
+            xx = 1;
+        } else if (!strcasecmp(opt,"gt")) {
+            *flags |= EXPIRE_GT;
+            gt = 1;
+        } else if (!strcasecmp(opt,"lt")) {
+            *flags |= EXPIRE_LT;
+            lt = 1;
+        } else {
+            addReplyErrorFormat(c, "Unsupported option %s", opt);
+            return C_ERR;
+        }
+        j++;
+    }
+
+    if ((nx && xx) || (nx && gt) || (nx && lt)) {
+        addReplyError(c, "NX and XX, GT or LT options at the same time are not compatible");
+        return C_ERR;
+    }
+
+    if (gt && lt) {
+        addReplyError(c, "GT and LT options at the same time are not compatible");
+        return C_ERR;
+    }
+
+    return C_OK;
+}
+
+/*-----------------------------------------------------------------------------
+ * Expires Commands
+ *----------------------------------------------------------------------------*/
+
+/* This is the generic command implementation for EXPIRE, PEXPIRE, EXPIREAT
+ * and PEXPIREAT. Because the command second argument may be relative or absolute
+ * the "basetime" argument is used to signal what the base time is (either 0
+ * for *AT variants of the command, or the current time for relative expires).
+ *
+ * unit is either UNIT_SECONDS or UNIT_MILLISECONDS, and is only used for
+ * the argv[2] parameter. The basetime is always specified in milliseconds.
+ *
+ * Additional flags are supported and parsed via parseExtendedExpireArguments */
+void expireGenericCommand(client *c, long long basetime, int unit) {
+    robj *key = c->argv[1], *param = c->argv[2];
+    long long when; /* unix time in milliseconds when the key will expire. */
+    long long current_expire = -1;
+    int flag = 0;
+
+    /* checking optional flags */
+    if (parseExtendedExpireArgumentsOrReply(c, &flag) != C_OK) {
+        return;
+    }
+
+    if (getLongLongFromObjectOrReply(c, param, &when, NULL) != C_OK)
+        return;
+
+    /* EXPIRE allows negative numbers, but we can at least detect an
+     * overflow by either unit conversion or basetime addition. */
+    if (unit == UNIT_SECONDS) {
+        if (when > LLONG_MAX / 1000 || when < LLONG_MIN / 1000) {
+            addReplyErrorExpireTime(c);
+            return;
+        }
+        when *= 1000;
+    }
+
+    if (when > LLONG_MAX - basetime) {
+        addReplyErrorExpireTime(c);
+        return;
+    }
+    when += basetime;
+
+    /* No key, return zero. */
+    if (lookupKeyWrite(c->db,key) == NULL) {
+        addReply(c,shared.czero);
+        return;
+    }
+
+    if (flag) {
+        current_expire = getExpire(c->db, key);
+
+        /* NX option is set, check current expiry */
+        if (flag & EXPIRE_NX) {
+            if (current_expire != -1) {
+                addReply(c,shared.czero);
+                return;
+            }
+        }
+
+        /* XX option is set, check current expiry */
+        if (flag & EXPIRE_XX) {
+            if (current_expire == -1) {
+                /* reply 0 when the key has no expiry */
+                addReply(c,shared.czero);
+                return;
+            }
+        }
+
+        /* GT option is set, check current expiry */
+        if (flag & EXPIRE_GT) {
+            /* When current_expire is -1, we consider it as infinite TTL,
+             * so expire command with gt always fail the GT. */
+            if (when <= current_expire || current_expire == -1) {
+                /* reply 0 when the new expiry is not greater than current */
+                addReply(c,shared.czero);
+                return;
+            }
+        }
+
+        /* LT option is set, check current expiry */
+        if (flag & EXPIRE_LT) {
+            /* When current_expire -1, we consider it as infinite TTL,
+             * but 'when' can still be negative at this point, so if there is
+             * an expiry on the key and it's not less than current, we fail the LT. */
+            if (current_expire != -1 && when >= current_expire) {
+                /* reply 0 when the new expiry is not less than current */
+                addReply(c,shared.czero);
+                return;
+            }
+        }
+    }
+
+    if (checkAlreadyExpired(when)) {
+        robj *aux;
+
+        int deleted = server.lazyfree_lazy_expire ? dbAsyncDelete(c->db,key) :
+                                                    dbSyncDelete(c->db,key);
+        serverAssertWithInfo(c,key,deleted);
+        server.dirty++;
+
+        /* Replicate/AOF this as an explicit DEL or UNLINK. */
+        aux = server.lazyfree_lazy_expire ? shared.unlink : shared.del;
+        rewriteClientCommandVector(c,2,aux,key);
+        signalModifiedKey(c,c->db,key);
+        notifyKeyspaceEvent(NOTIFY_GENERIC,"del",key,c->db->id);
+        addReply(c, shared.cone);
+        return;
+    } else {
+        setExpire(c,c->db,key,when);
+        addReply(c,shared.cone);
+        /* Propagate as PEXPIREAT millisecond-timestamp
+         * Only rewrite the command arg if not already PEXPIREAT */
+        if (c->cmd->proc != pexpireatCommand) {
+            rewriteClientCommandArgument(c,0,shared.pexpireat);
+        }
+
+        /* Avoid creating a string object when it's the same as argv[2] parameter  */
+        if (basetime != 0 || unit == UNIT_SECONDS) {
+            robj *when_obj = createStringObjectFromLongLong(when);
+            rewriteClientCommandArgument(c,2,when_obj);
+            decrRefCount(when_obj);
+        }
+
+        signalModifiedKey(c,c->db,key);
+        notifyKeyspaceEvent(NOTIFY_GENERIC,"expire",key,c->db->id);
+        server.dirty++;
+        return;
+    }
+}
+
+/* EXPIRE key seconds [ NX | XX | GT | LT] */
+void expireCommand(client *c) {
+    expireGenericCommand(c,mstime(),UNIT_SECONDS);
+}
+
+/* EXPIREAT key unix-time-seconds [ NX | XX | GT | LT] */
+void expireatCommand(client *c) {
+    expireGenericCommand(c,0,UNIT_SECONDS);
+}
+
+/* PEXPIRE key milliseconds [ NX | XX | GT | LT] */
+void pexpireCommand(client *c) {
+    expireGenericCommand(c,mstime(),UNIT_MILLISECONDS);
+}
+
+/* PEXPIREAT key unix-time-milliseconds [ NX | XX | GT | LT] */
+void pexpireatCommand(client *c) {
+    expireGenericCommand(c,0,UNIT_MILLISECONDS);
+}
+
+/* Implements TTL, PTTL, EXPIRETIME and PEXPIRETIME */
+void ttlGenericCommand(client *c, int output_ms, int output_abs) {
+    long long expire, ttl = -1;
+
+    /* If the key does not exist at all, return -2 */
+    if (lookupKeyReadWithFlags(c->db,c->argv[1],LOOKUP_NOTOUCH) == NULL) {
+        addReplyLongLong(c,-2);
+        return;
+    }
+
+    /* The key exists. Return -1 if it has no expire, or the actual
+     * TTL value otherwise. */
+    expire = getExpire(c->db,c->argv[1]);
+    if (expire != -1) {
+        ttl = output_abs ? expire : expire-mstime();
+        if (ttl < 0) ttl = 0;
+    }
+    if (ttl == -1) {
+        addReplyLongLong(c,-1);
+    } else {
+        addReplyLongLong(c,output_ms ? ttl : ((ttl+500)/1000));
+    }
+}
+
+/* TTL key */
+void ttlCommand(client *c) {
+    ttlGenericCommand(c, 0, 0);
+}
+
+/* PTTL key */
+void pttlCommand(client *c) {
+    ttlGenericCommand(c, 1, 0);
+}
+
+/* EXPIRETIME key */
+void expiretimeCommand(client *c) {
+    ttlGenericCommand(c, 0, 1);
+}
+
+/* PEXPIRETIME key */
+void pexpiretimeCommand(client *c) {
+    ttlGenericCommand(c, 1, 1);
+}
+
+/* PERSIST key */
+void persistCommand(client *c) {
+    if (lookupKeyWrite(c->db,c->argv[1])) {
+        if (removeExpire(c->db,c->argv[1])) {
+            signalModifiedKey(c,c->db,c->argv[1]);
+            notifyKeyspaceEvent(NOTIFY_GENERIC,"persist",c->argv[1],c->db->id);
+            addReply(c,shared.cone);
+            server.dirty++;
+        } else {
+            addReply(c,shared.czero);
+        }
+    } else {
+        addReply(c,shared.czero);
+    }
+}
+
+/* TOUCH key1 [key2 key3 ... keyN] */
+void touchCommand(client *c) {
+    int touched = 0;
+    for (int j = 1; j < c->argc; j++)
+        if (lookupKeyRead(c->db,c->argv[j]) != NULL) touched++;
+    addReplyLongLong(c,touched);
+}