Do not update the LRU info on key lookup when we have a saving child. With this trivi...

[redis.git] / src / object.c

diff --git a/src/object.c b/src/object.c
index c1a0824515bfaf12394520bb493efc7363f4396e..b1eae96329ebe59a4cdc7366d8ca0d393ed27761 100644 (file)
--- a/src/object.c
+++ b/src/object.c
@@ -19,14 +19,19 @@ robj *createObject(int type, void *ptr) {
     o->encoding = REDIS_ENCODING_RAW;
     o->ptr = ptr;
     o->refcount = 1;
-    if (server.vm_enabled) {
-        /* Note that this code may run in the context of an I/O thread
-         * and accessing server.lruclock in theory is an error
-         * (no locks). But in practice this is safe, and even if we read
-         * garbage Redis will not fail. */
-        o->lru = server.lruclock;
-        o->storage = REDIS_VM_MEMORY;
-    }
+    /* Set the LRU to the current lruclock (minutes resolution).
+     * We do this regardless of the fact VM is active as LRU is also
+     * used for the maxmemory directive when Redis is used as cache.
+     *
+     * Note that this code may run in the context of an I/O thread
+     * and accessing server.lruclock in theory is an error
+     * (no locks). But in practice this is safe, and even if we read
+     * garbage Redis will not fail. */
+    o->lru = server.lruclock;
+    /* The following is only needed if VM is active, but since the conditional
+     * is probably more costly than initializing the field it's better to
+     * have every field properly initialized anyway. */
+    o->storage = REDIS_VM_MEMORY;
     return o;
 }
 
@@ -240,8 +245,12 @@ robj *tryObjectEncoding(robj *o) {
      * range and if this is the main thread, since when VM is enabled we
      * have the constraint that I/O thread should only handle non-shared
      * objects, in order to avoid race conditions (we don't have per-object
-     * locking). */
-    if (value >= 0 && value < REDIS_SHARED_INTEGERS &&
+     * locking).
+     *
+     * Note that we also avoid using shared integers when maxmemory is used
+     * because very object needs to have a private LRU field for the LRU
+     * algorithm to work well. */
+    if (server.maxmemory == 0 && value >= 0 && value < REDIS_SHARED_INTEGERS &&
         pthread_equal(pthread_self(),server.mainthread)) {
         decrRefCount(o);
         incrRefCount(shared.integers[value]);
@@ -433,3 +442,14 @@ char *strEncoding(int encoding) {
     default: return "unknown";
     }
 }
+
+/* Given an object returns the min number of seconds the object was never
+ * requested, using an approximated LRU algorithm. */
+unsigned long estimateObjectIdleTime(robj *o) {
+    if (server.lruclock >= o->lru) {
+        return (server.lruclock - o->lru) * REDIS_LRU_CLOCK_RESOLUTION;
+    } else {
+        return ((REDIS_LRU_CLOCK_MAX - o->lru) + server.lruclock) *
+                    REDIS_LRU_CLOCK_RESOLUTION;
+    }
+}