Merge pull request #2013 from phpredis/improved-liveness-detection-rebase

michael-grunder · web-flow · commit 42e69d8e1770 · 2021-10-05T08:31:18.000-07:00
Experimental support to detect unconsumed data
diff --git a/common.h b/common.h
@@ -134,6 +134,17 @@ typedef enum {
 #define MULTI    1
 #define PIPELINE 2
 
+#define PHPREDIS_DEBUG_LOGGING 0
+
+#if PHPREDIS_DEBUG_LOGGING == 1
+#define redisDbgFmt(fmt, ...) \
+    php_printf("%s:%d:%s(): " fmt "\n", __FILE__, __LINE__, __func__, __VA_ARGS__)
+#define redisDbgStr(str) phpredisDebugFmt("%s", str)
+#else
+#define redisDbgFmt(fmt, ...) ((void)0)
+#define redisDbgStr(str) ((void)0)
+#endif
+
 #define IS_ATOMIC(redis_sock) (redis_sock->mode == ATOMIC)
 #define IS_MULTI(redis_sock) (redis_sock->mode & MULTI)
 #define IS_PIPELINE(redis_sock) (redis_sock->mode & PIPELINE)
diff --git a/library.c b/library.c
@@ -2182,6 +2182,82 @@ static int redis_stream_liveness_check(php_stream *stream) {
                                  SUCCESS : FAILURE;
 }
 
+/* Try to get the underlying socket FD for use with poll/select.
+ * Returns -1 on failure. */
+static php_socket_t redis_stream_fd_for_select(php_stream *stream) {
+    php_socket_t fd;
+    int flags;
+
+    flags = PHP_STREAM_AS_FD_FOR_SELECT | PHP_STREAM_CAST_INTERNAL;
+    if (php_stream_cast(stream, flags, (void*)&fd, 1) == FAILURE)
+        return -1;
+
+    return fd;
+}
+
+static int redis_detect_dirty_config(void) {
+    int val = INI_INT("redis.pconnect.pool_detect_dirty");
+
+    if (val >= 0 && val <= 2)
+        return val;
+    else if (val > 2)
+        return 2;
+    else
+        return 0;
+}
+
+static int redis_pool_poll_timeout(void) {
+    int val = INI_INT("redis.pconnect.pool_poll_timeout");
+    if (val >= 0)
+        return val;
+
+    return 0;
+}
+
+#define REDIS_POLL_FD_SET(_pfd, _fd, _events) \
+    (_pfd).fd = _fd; (_pfd).events = _events; (_pfd).revents = 0
+
+/* Try to determine if the socket is out of sync (has unconsumed replies) */
+static int redis_stream_detect_dirty(php_stream *stream) {
+    php_socket_t fd;
+    php_pollfd pfd;
+    int rv, action;
+
+    /* Short circuit if this is disabled */
+    if ((action = redis_detect_dirty_config()) == 0)
+        return SUCCESS;
+
+    /* Seek past unconsumed bytes if we detect them */
+    if (stream->readpos < stream->writepos) {
+        redisDbgFmt("%s on unconsumed buffer (%ld < %ld)",
+                    action > 1 ? "Aborting" : "Seeking",
+                    (long)stream->readpos, (long)stream->writepos);
+
+        /* Abort if we are configured to immediately fail */
+        if (action == 1)
+            return FAILURE;
+
+        /* Seek to the end of buffered data */
+        zend_off_t offset = stream->writepos - stream->readpos;
+        if (php_stream_seek(stream, offset, SEEK_CUR) == FAILURE)
+            return FAILURE;
+    }
+
+    /* Get the underlying FD */
+    if ((fd = redis_stream_fd_for_select(stream)) == -1)
+        return FAILURE;
+
+    /* We want to detect a readable socket (it shouln't be) */
+    REDIS_POLL_FD_SET(pfd, fd, PHP_POLLREADABLE);
+    rv = php_poll2(&pfd, 1, redis_pool_poll_timeout());
+
+    /* If we detect the socket is readable, it's dirty which is
+     * a failure.  Otherwise as best we can tell it's good.
+     * TODO:  We could attempt to consume up to N bytes */
+    redisDbgFmt("Detected %s socket", rv > 0 ? "readable" : "unreadable");
+    return rv == 0 ? SUCCESS : FAILURE;
+}
+
 static int
 redis_sock_check_liveness(RedisSock *redis_sock)
 {
@@ -2190,11 +2266,14 @@ redis_sock_check_liveness(RedisSock *redis_sock)
     smart_string cmd = {0};
     size_t len;
 
-    /* Short circuit if we detect the stream has gone bad or if the user has
-     * configured persistent connection "YOLO mode". */
-    if (redis_stream_liveness_check(redis_sock->stream) != SUCCESS) {
+    /* Short circuit if PHP detects the stream isn't live */
+    if (redis_stream_liveness_check(redis_sock->stream) != SUCCESS)
+        goto failure;
+
+    /* Short circuit if we detect the stream is "dirty", can't or are
+       configured not to try and fix it */
+    if (redis_stream_detect_dirty(redis_sock->stream) != SUCCESS)
         goto failure;
-    }
 
     redis_sock->status = REDIS_SOCK_STATUS_CONNECTED;
     if (!INI_INT("redis.pconnect.echo_check_liveness")) {
@@ -2313,6 +2392,7 @@ PHP_REDIS_API int redis_sock_connect(RedisSock *redis_sock)
                 if (redis_sock_check_liveness(redis_sock) == SUCCESS) {
                     return SUCCESS;
                 }
+
                 p->nb_active--;
             }
 
diff --git a/redis.c b/redis.c
@@ -104,6 +104,8 @@ PHP_INI_BEGIN()
     PHP_INI_ENTRY("redis.pconnect.pooling_enabled", "1", PHP_INI_ALL, NULL)
     PHP_INI_ENTRY("redis.pconnect.connection_limit", "0", PHP_INI_ALL, NULL)
     PHP_INI_ENTRY("redis.pconnect.echo_check_liveness", "1", PHP_INI_ALL, NULL)
+    PHP_INI_ENTRY("redis.pconnect.pool_detect_dirty", "0", PHP_INI_ALL, NULL)
+    PHP_INI_ENTRY("redis.pconnect.pool_poll_timeout", "0", PHP_INI_ALL, NULL)
     PHP_INI_ENTRY("redis.pconnect.pool_pattern", "", PHP_INI_ALL, NULL)
 
     /* redis session */
