Add RedisModule adapter (#1182)

* Add RedisModule adapter
* add timer callback, add compatibility helper

2 files changed, 245 insertions, 0 deletions

diff --git a/adapters/redismoduleapi.h b/adapters/redismoduleapi.h
new file mode 100644
index 0000000..8a076fe
--- /dev/null
+++ b/adapters/redismoduleapi.h
@@ -0,0 +1,144 @@
+#ifndef __HIREDIS_REDISMODULEAPI_H__
+#define __HIREDIS_REDISMODULEAPI_H__
+
+#include "redismodule.h"
+
+#include "../async.h"
+#include "../hiredis.h"
+
+#include <sys/types.h>
+
+typedef struct redisModuleEvents {
+    redisAsyncContext *context;
+    RedisModuleCtx *module_ctx;
+    int fd;
+    int reading, writing;
+    int timer_active;
+    RedisModuleTimerID timer_id;
+} redisModuleEvents;
+
+static inline void redisModuleReadEvent(int fd, void *privdata, int mask) {
+    (void) fd;
+    (void) mask;
+
+    redisModuleEvents *e = (redisModuleEvents*)privdata;
+    redisAsyncHandleRead(e->context);
+}
+
+static inline void redisModuleWriteEvent(int fd, void *privdata, int mask) {
+    (void) fd;
+    (void) mask;
+
+    redisModuleEvents *e = (redisModuleEvents*)privdata;
+    redisAsyncHandleWrite(e->context);
+}
+
+static inline void redisModuleAddRead(void *privdata) {
+    redisModuleEvents *e = (redisModuleEvents*)privdata;
+    if (!e->reading) {
+        e->reading = 1;
+        RedisModule_EventLoopAdd(e->fd, REDISMODULE_EVENTLOOP_READABLE, redisModuleReadEvent, e);
+    }
+}
+
+static inline void redisModuleDelRead(void *privdata) {
+    redisModuleEvents *e = (redisModuleEvents*)privdata;
+    if (e->reading) {
+        e->reading = 0;
+        RedisModule_EventLoopDel(e->fd, REDISMODULE_EVENTLOOP_READABLE);
+    }
+}
+
+static inline void redisModuleAddWrite(void *privdata) {
+    redisModuleEvents *e = (redisModuleEvents*)privdata;
+    if (!e->writing) {
+        e->writing = 1;
+        RedisModule_EventLoopAdd(e->fd, REDISMODULE_EVENTLOOP_WRITABLE, redisModuleWriteEvent, e);
+    }
+}
+
+static inline void redisModuleDelWrite(void *privdata) {
+    redisModuleEvents *e = (redisModuleEvents*)privdata;
+    if (e->writing) {
+        e->writing = 0;
+        RedisModule_EventLoopDel(e->fd, REDISMODULE_EVENTLOOP_WRITABLE);
+    }
+}
+
+static inline void redisModuleStopTimer(void *privdata) {
+    redisModuleEvents *e = (redisModuleEvents*)privdata;
+    if (e->timer_active) {
+        RedisModule_StopTimer(e->module_ctx, e->timer_id, NULL);
+    }
+    e->timer_active = 0;
+}
+
+static inline void redisModuleCleanup(void *privdata) {
+    redisModuleEvents *e = (redisModuleEvents*)privdata;
+    redisModuleDelRead(privdata);
+    redisModuleDelWrite(privdata);
+    redisModuleStopTimer(privdata);
+    hi_free(e);
+}
+
+static inline void redisModuleTimeout(RedisModuleCtx *ctx, void *privdata) {
+    (void) ctx;
+
+    redisModuleEvents *e = (redisModuleEvents*)privdata;
+    e->timer_active = 0;
+    redisAsyncHandleTimeout(e->context);
+}
+
+static inline void redisModuleSetTimeout(void *privdata, struct timeval tv) {
+    redisModuleEvents* e = (redisModuleEvents*)privdata;
+
+    redisModuleStopTimer(privdata);
+
+    mstime_t millis = tv.tv_sec * 1000 + tv.tv_usec / 1000.0;
+    e->timer_id = RedisModule_CreateTimer(e->module_ctx, millis, redisModuleTimeout, e);
+    e->timer_active = 1;
+}
+
+/* Check if Redis version is compatible with the adapter. */
+static inline int redisModuleCompatibilityCheck(void) {
+    if (!RedisModule_EventLoopAdd ||
+        !RedisModule_EventLoopDel ||
+        !RedisModule_CreateTimer ||
+        !RedisModule_StopTimer) {
+        return REDIS_ERR;
+    }
+    return REDIS_OK;
+}
+
+static inline int redisModuleAttach(redisAsyncContext *ac, RedisModuleCtx *module_ctx) {
+    redisContext *c = &(ac->c);
+    redisModuleEvents *e;
+
+    /* Nothing should be attached when something is already attached */
+    if (ac->ev.data != NULL)
+        return REDIS_ERR;
+
+    /* Create container for context and r/w events */
+    e = (redisModuleEvents*)hi_malloc(sizeof(*e));
+    if (e == NULL)
+        return REDIS_ERR;
+
+    e->context = ac;
+    e->module_ctx = module_ctx;
+    e->fd = c->fd;
+    e->reading = e->writing = 0;
+    e->timer_active = 0;
+
+    /* Register functions to start/stop listening for events */
+    ac->ev.addRead = redisModuleAddRead;
+    ac->ev.delRead = redisModuleDelRead;
+    ac->ev.addWrite = redisModuleAddWrite;
+    ac->ev.delWrite = redisModuleDelWrite;
+    ac->ev.cleanup = redisModuleCleanup;
+    ac->ev.scheduleTimer = redisModuleSetTimeout;
+    ac->ev.data = e;
+
+    return REDIS_OK;
+}
+
+#endif
diff --git a/examples/example-redismoduleapi.c b/examples/example-redismoduleapi.c
new file mode 100644
index 0000000..7d12f8a
--- /dev/null
+++ b/examples/example-redismoduleapi.c
@@ -0,0 +1,101 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <signal.h>
+
+#include <hiredis.h>
+#include <async.h>
+#include <adapters/redismoduleapi.h>
+
+void debugCallback(redisAsyncContext *c, void *r, void *privdata) {
+    (void)privdata; //unused
+    redisReply *reply = r;
+    if (reply == NULL) {
+        /* The DEBUG SLEEP command will almost always fail, because we have set a 1 second timeout */
+        printf("`DEBUG SLEEP` error: %s\n", c->errstr ? c->errstr : "unknown error");
+        return;
+    }
+    /* Disconnect after receiving the reply of DEBUG SLEEP (which will not)*/
+    redisAsyncDisconnect(c);
+}
+
+void getCallback(redisAsyncContext *c, void *r, void *privdata) {
+    redisReply *reply = r;
+    if (reply == NULL) {
+        if (c->errstr) {
+            printf("errstr: %s\n", c->errstr);
+        }
+        return;
+    }
+    printf("argv[%s]: %s\n", (char*)privdata, reply->str);
+
+    /* start another request that demonstrate timeout */
+    redisAsyncCommand(c, debugCallback, NULL, "DEBUG SLEEP %f", 1.5);
+}
+
+void connectCallback(const redisAsyncContext *c, int status) {
+    if (status != REDIS_OK) {
+        printf("Error: %s\n", c->errstr);
+        return;
+    }
+    printf("Connected...\n");
+}
+
+void disconnectCallback(const redisAsyncContext *c, int status) {
+    if (status != REDIS_OK) {
+        printf("Error: %s\n", c->errstr);
+        return;
+    }
+    printf("Disconnected...\n");
+}
+
+/*
+ * This example requires Redis 7.0 or above.
+ *
+ * 1- Compile this file as a shared library. Directory of "redismodule.h" must
+ *    be in the include path.
+ *       gcc -fPIC -shared -I../../redis/src/ -I.. example-redismoduleapi.c -o example-redismoduleapi.so
+ *
+ * 2- Load module:
+ *       redis-server --loadmodule ./example-redismoduleapi.so value
+ */
+int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+
+    int ret = RedisModule_Init(ctx, "example-redismoduleapi", 1, REDISMODULE_APIVER_1);
+    if (ret != REDISMODULE_OK) {
+        printf("error module init \n");
+        return REDISMODULE_ERR;
+    }
+
+    if (redisModuleCompatibilityCheck() != REDIS_OK) {
+        printf("Redis 7.0 or above is required! \n");
+        return REDISMODULE_ERR;
+    }
+
+    redisAsyncContext *c = redisAsyncConnect("127.0.0.1", 6379);
+    if (c->err) {
+        /* Let *c leak for now... */
+        printf("Error: %s\n", c->errstr);
+        return 1;
+    }
+
+    size_t len;
+    const char *val = RedisModule_StringPtrLen(argv[argc-1], &len);
+
+    RedisModuleCtx *module_ctx = RedisModule_GetDetachedThreadSafeContext(ctx);
+    redisModuleAttach(c, module_ctx);
+    redisAsyncSetConnectCallback(c,connectCallback);
+    redisAsyncSetDisconnectCallback(c,disconnectCallback);
+    redisAsyncSetTimeout(c, (struct timeval){ .tv_sec = 1, .tv_usec = 0});
+
+    /*
+    In this demo, we first `set key`, then `get key` to demonstrate the basic usage of the adapter.
+    Then in `getCallback`, we start a `debug sleep` command to create 1.5 second long request.
+    Because we have set a 1 second timeout to the connection, the command will always fail with a
+    timeout error, which is shown in the `debugCallback`.
+    */
+
+    redisAsyncCommand(c, NULL, NULL, "SET key %b", val, len);
+    redisAsyncCommand(c, getCallback, (char*)"end-1", "GET key");
+    return 0;
+}