/* * Copyright (c) 2020, Michael Grunder * * 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 #include #include #include #include #define KEY_COUNT 5 #define panicAbort(fmt, ...) \ do { \ fprintf(stderr, "%s:%d:%s(): " fmt, __FILE__, __LINE__, __func__, __VA_ARGS__); \ exit(-1); \ } while (0) static void assertReplyAndFree(redisContext *context, redisReply *reply, int type) { if (reply == NULL) panicAbort("NULL reply from server (error: %s)", context->errstr); if (reply->type != type) { if (reply->type == REDIS_REPLY_ERROR) fprintf(stderr, "Redis Error: %s\n", reply->str); panicAbort("Expected reply type %d but got type %d", type, reply->type); } freeReplyObject(reply); } /* Switch to the RESP3 protocol and enable client tracking */ static void enableClientTracking(redisContext *c) { redisReply *reply = redisCommand(c, "HELLO 3"); if (reply == NULL || c->err) { panicAbort("NULL reply or server error (error: %s)", c->errstr); } if (reply->type != REDIS_REPLY_MAP) { fprintf(stderr, "Error: Can't send HELLO 3 command. Are you sure you're "); fprintf(stderr, "connected to redis-server >= 6.0.0?\nRedis error: %s\n", reply->type == REDIS_REPLY_ERROR ? reply->str : "(unknown)"); exit(-1); } freeReplyObject(reply); /* Enable client tracking */ reply = redisCommand(c, "CLIENT TRACKING ON"); assertReplyAndFree(c, reply, REDIS_REPLY_STATUS); } void pushReplyHandler(void *privdata, void *r) { redisReply *reply = r; int *invalidations = privdata; /* Sanity check on the invalidation reply */ if (reply->type != REDIS_REPLY_PUSH || reply->elements != 2 || reply->element[1]->type != REDIS_REPLY_ARRAY || reply->element[1]->element[0]->type != REDIS_REPLY_STRING) { panicAbort("%s", "Can't parse PUSH message!"); } /* Increment our invalidation count */ *invalidations += 1; printf("pushReplyHandler(): INVALIDATE '%s' (invalidation count: %d)\n", reply->element[1]->element[0]->str, *invalidations); freeReplyObject(reply); } /* We aren't actually freeing anything here, but it is included to show that we can * have hiredis call our data destructor when freeing the context */ void privdata_dtor(void *privdata) { unsigned int *icount = privdata; printf("privdata_dtor(): In context privdata dtor (invalidations: %u)\n", *icount); } int main(int argc, char **argv) { unsigned int j, invalidations = 0; redisContext *c; redisReply *reply; const char *hostname = (argc > 1) ? argv[1] : "127.0.0.1"; int port = (argc > 2) ? atoi(argv[2]) : 6379; redisOptions o = {0}; REDIS_OPTIONS_SET_TCP(&o, hostname, port); /* Set our context privdata to the address of our invalidation counter. Each * time our PUSH handler is called, hiredis will pass the privdata for context. * * This could also be done after we create the context like so: * * c->privdata = &invalidations; * c->free_privdata = privdata_dtor; */ REDIS_OPTIONS_SET_PRIVDATA(&o, &invalidations, privdata_dtor); /* Set our custom PUSH message handler */ o.push_cb = pushReplyHandler; c = redisConnectWithOptions(&o); if (c == NULL || c->err) panicAbort("Connection error: %s", c ? c->errstr : "OOM"); /* Enable RESP3 and turn on client tracking */ enableClientTracking(c); /* Set some keys and then read them back. Once we do that, Redis will deliver * invalidation push messages whenever the key is modified */ for (j = 0; j < KEY_COUNT; j++) { reply = redisCommand(c, "SET key:%d initial:%d", j, j); assertReplyAndFree(c, reply, REDIS_REPLY_STATUS); reply = redisCommand(c, "GET key:%d", j); assertReplyAndFree(c, reply, REDIS_REPLY_STRING); } /* Trigger invalidation messages by updating keys we just read */ for (j = 0; j < KEY_COUNT; j++) { printf(" main(): SET key:%d update:%d\n", j, j); reply = redisCommand(c, "SET key:%d update:%d", j, j); assertReplyAndFree(c, reply, REDIS_REPLY_STATUS); printf(" main(): SET REPLY OK\n"); } printf("\nTotal detected invalidations: %d, expected: %d\n", invalidations, KEY_COUNT); /* PING server */ redisFree(c); }