First implementation of the slow log feature

1 files changed, 111 insertions, 0 deletions

diff --git a/src/slowlog.c b/src/slowlog.c
new file mode 100644
index 000000000..ecaf65080
--- /dev/null
+++ b/src/slowlog.c
@@ -0,0 +1,111 @@
+#include "redis.h"
+#include "slowlog.h"
+
+/* Slowlog implements a system that is able to remember the latest N
+ * queries that took more than M microseconds to execute.
+ *
+ * The execution time to reach to be logged in the slow log is set
+ * using the 'slowlog-log-slower-than' config directive, that is also
+ * readable and writable using the CONFIG SET/GET command.
+ *
+ * The slow queries log is actually not "logged" in the Redis log file
+ * but is accessible thanks to the SLOWLOG command. */
+
+/* Create a new slowlog entry.
+ * Incrementing the ref count of all the objects retained is up to
+ * this function. */
+slowlogEntry *slowlogCreateEntry(robj **argv, int argc, long long duration) {
+    slowlogEntry *se = zmalloc(sizeof(*se));
+    int j;
+
+    se->argc = argc;
+    se->argv = zmalloc(sizeof(robj*)*argc);
+    for (j = 0; j < argc; j++) {
+        se->argv[j] = argv[j];
+        incrRefCount(argv[j]);
+    }
+    se->time = time(NULL);
+    se->duration = duration;
+    return se;
+}
+
+/* Free a slow log entry. The argument is void so that the prototype of this
+ * function matches the one of the 'free' method of adlist.c.
+ *
+ * This function will take care to release all the retained object. */
+void slowlogFreeEntry(void *septr) {
+    slowlogEntry *se = septr;
+    int j;
+
+    for (j = 0; j < se->argc; j++)
+        decrRefCount(se->argv[j]);
+    zfree(se->argv);
+    zfree(se);
+}
+
+/* Initialize the slow log. This function should be called a single time
+ * at server startup. */
+void slowlogInit(void) {
+    server.slowlog = listCreate();
+    listSetFreeMethod(server.slowlog,slowlogFreeEntry);
+}
+
+/* Push a new entry into the slow log.
+ * This function will make sure to trim the slow log accordingly to the
+ * configured max length. */
+void slowlogPushEntryIfNeeded(robj **argv, int argc, long long duration) {
+    if (duration > server.slowlog_log_slower_than)
+        listAddNodeHead(server.slowlog,slowlogCreateEntry(argv,argc,duration));
+
+    /* Remove old entries if needed. */
+    while (listLength(server.slowlog) > server.slowlog_max_len)
+        listDelNode(server.slowlog,listLast(server.slowlog));
+}
+
+/* Remove all the entries from the current slow log. */
+void slowlogReset(void) {
+    while (listLength(server.slowlog) > 0)
+        listDelNode(server.slowlog,listLast(server.slowlog));
+}
+
+/* The SLOWLOG command. Implements all the subcommands needed to handle the
+ * Redis slow log. */
+void slowlogCommand(redisClient *c) {
+    if (c->argc == 2 && !strcasecmp(c->argv[1]->ptr,"reset")) {
+        slowlogReset();
+        addReply(c,shared.ok);
+    } else if (c->argc == 2 && !strcasecmp(c->argv[1]->ptr,"len")) {
+        addReplyLongLong(c,listLength(server.slowlog));
+    } else if ((c->argc == 2 || c->argc == 3) &&
+               !strcasecmp(c->argv[1]->ptr,"get"))
+    {
+        long count = 10, sent = 0;
+        listIter li;
+        void *totentries;
+        listNode *ln;
+        slowlogEntry *se;
+
+        if (c->argc == 3 &&
+            getLongFromObjectOrReply(c,c->argv[2],&count,NULL) != REDIS_OK)
+            return;
+
+        listRewind(server.slowlog,&li);
+        totentries = addDeferredMultiBulkLength(c);
+        while(count-- && (ln = listNext(&li))) {
+            int j;
+
+            se = ln->value;
+            addReplyMultiBulkLen(c,3);
+            addReplyLongLong(c,se->time);
+            addReplyLongLong(c,se->duration);
+            addReplyMultiBulkLen(c,se->argc);
+            for (j = 0; j < se->argc; j++)
+                addReplyBulk(c,se->argv[j]);
+            sent++;
+        }
+        setDeferredMultiBulkLength(c,totentries,sent);
+    } else {
+        addReplyError(c,
+            "Unknown SLOWLOG subcommand or wrong # of args. Try GET, RESET, LEN.");
+    }
+}