Changeset 635

Timestamp:

11/15/07 08:13:45 (1 year ago)

Author:

dormando

Message:

CAS fix from Christ Goffinet and Dustin Sallings. Use a global incremental
counter in a thread safe place.

Files:

• trunk/server/items.c (modified) (3 diffs)
• trunk/server/memcached.c (modified) (10 diffs)
• trunk/server/memcached.h (modified) (3 diffs)

trunk/server/items.c

@@ -18 +18 @@
-static void item_link_q(item *it);
-static void item_unlink_q(item *it);
+static uint64_t get_cas_id();
-
-/*
@@ -38 +39 @@
-        sizes[i] = 0;
-    }
+}
+
+/* Get the next CAS id for a new item. */
+uint64_t get_cas_id() {
+    static uint64_t cas_id;
+    if(cas_id >= MAX_CAS_ID) {
+        cas_id = 0;
+    }
+    return ++cas_id;
-}
-
@@ -130 +140 @@
-    it->nkey = nkey;
-    it->nbytes = nbytes;
+    it->cas_id = get_cas_id();
-    strcpy(ITEM_key(it), key);
-    it->exptime = exptime;

trunk/server/memcached.c

@@ -690 +690 @@
-    item *it = c->item;
-    int comm = c->item_comm;
+    int ret;
-
-    STATS_LOCK();
@@ -698 +699 @@
-        out_string(c, "CLIENT_ERROR bad data chunk");
-    } else {
-
-
-
-
-
+
+
+
+
+
+
+
+
+
-    }
-
@@ -735 +740 @@
-    {
-        /* replace and add can't override delete locks; don't store */
+    } else if (comm == NREAD_CAS) {
+        /* validate cas operation */
+        if (delete_locked)
+            old_it = do_item_get_nocheck(key, it->nkey);
+
+        if(old_it == NULL) {
+          // LRU expired
+          stored = 3;
+        }
+        else if(it->cas_id == old_it->cas_id) {
+          // cas validates
+          do_item_replace(old_it, it);
+          stored = 1;
+        }
+        else
+        {
+          stored = 2;
+        }
-    } else {
-
-        /*
-         * Append - combine new and old record into single one. Here it's
@@ -1081 +1103 @@
-    token_t *key_token = &tokens[KEY_TOKEN];
-    char suffix[255];
-    uint32_t in_memory_ptr;
-    assert(c != NULL);
-
@@ -1134 +1155 @@
-                if(return_key_ptr == true)
-                {
-in_memory_ptr = (uint32_t)item_get(key, nkey);
-sprintf(suffix," %d %d %lu\r\n", atoi(ITEM_suffix(it) + 1), it->nbytes - 2, in_memory_ptr
+sprintf(suffix," %d %d %llu\r\n", atoi(ITEM_suffix(it) + 1),
+    it->nbytes - 2, it->cas_id
-                  if (add_iov(c, "VALUE ", 6) != 0 ||
-                      add_iov(c, ITEM_key(it), it->nkey) != 0 ||
@@ -1214 +1235 @@
-    time_t exptime;
-    int vlen, old_vlen;
-32_t req_memory_ptr, in_memory_ptr
+64_t req_cas_id
-    item *it, *old_it;
-
@@ -1232 +1253 @@
-
-    // does cas value exist?
-tokens[5].value
+handle_cas
-    {
-memory_ptr
+cas_id
-    }
-
@@ -1260 +1281 @@
-
-    it = item_alloc(key, nkey, flags, realtime(exptime), vlen+2);
-
-    /* HANDLE_CAS VALIDATION */
-    if (handle_cas == true)
-    {
-      item *itmp=item_get(key, it->nkey);
-      /* Release the reference */
-      if(itmp) {
-        item_remove(itmp);
-      }
-      in_memory_ptr = (uint32_t)itmp;
-      if(in_memory_ptr == req_memory_ptr)
-      {
-        // validates allow the set
-      }
-      else if(in_memory_ptr)
-      {
-        out_string(c, "EXISTS");
-
-        /* swallow the data line */
-        c->write_and_go = conn_swallow;
-        c->sbytes = vlen + 2;
-        return;
-      }
-      else
-      {
-        out_string(c, "NOT FOUND");
-        /* swallow the data line */
-        c->write_and_go = conn_swallow;
-        c->sbytes = vlen + 2;
-        return;
-      }
-    }
-
-    if (it == 0) {
@@ -1303 +1292 @@
-        return;
-    }
+    if(handle_cas)
+      it->cas_id = req_cas_id;
-
-    c->item = it;
@@ -1546 +1537 @@
-        process_update_command(c, tokens, ntokens, comm, false);
-
-
+ && (comm = NREAD_CAS)
-
-        process_update_command(c, tokens, ntokens, comm, true);

trunk/server/memcached.h

@@ -32 +32 @@
-#define IOV_LIST_HIGHWAT 600
-#define MSG_LIST_HIGHWAT 100
+
+#define MAX_CAS_ID 0x7ffffffffffffff0
-
-/* Get a consistent bool type */
@@ -113 +115 @@
-    uint8_t         slabs_clsid;/* which slab class we're in */
-    uint8_t         nkey;       /* key length, w/terminating null and padding */
+    uint64_t        cas_id;     /* the CAS identifier */
-    void * end[];
-    /* then null-terminated key */
@@ -141 +144 @@
-#define NREAD_APPEND 4
-#define NREAD_PREPEND 5
+#define NREAD_CAS 6
-
-typedef struct {