Changeset 627

Timestamp:

10/03/07 23:45:44 (1 year ago)

Author:

plindner

Message:

update for prepend operation, thread safe version from Maxim replacing Filipe's implementation

Files:

• trunk/server/ChangeLog (modified) (1 diff)
• trunk/server/doc/protocol.txt (modified) (4 diffs)
• trunk/server/memcached.c (modified) (5 diffs)
• trunk/server/memcached.h (modified) (1 diff)

trunk/server/ChangeLog

@@ -15 +15 @@
-
-        * Add append command support written by Filipe Laborde.
-
+
+
-
-        * The memcached-tool script can now display stats.  Patch

trunk/server/doc/protocol.txt

@@ -54 +54 @@
-There are three types of commands. 
-
-five
-
+six
+"prepend" 
-client sends a command line, and then a data block; after that the
-client expects one line of response, which will indicate success or
@@ -127 +127 @@
-First, the client sends a command line which looks like this:
-
-
-
-
+cas 
+
+"prepend", 
-
-  "set" means "store this data".  
@@ -139 +139 @@
-  already hold data for this key".
-
-
+
+
+
-
-  "cas" is a check and set operation which means "store this data but
@@ -166 +168 @@
-
-- <cas unique> is a unique 64-bit value of an existing entry.
+  Clients should use the value returned from the "gets" command
+  when issuing "cas" updates.
-
-After this line, the client sends the data block:

trunk/server/memcached.c

@@ -720 +720 @@
-    int stored = 0;
-
+    item *new_it = NULL;
+    int flags;
+
-    if (old_it != NULL && comm == NREAD_ADD) {
-        /* add only adds a nonexistent item, but promote to head of LRU */
-        do_item_update(old_it);
-
+
+
+
-        /* replace only replaces an existing value; don't store */
-
+
+
+
-        /* replace and add can't override delete locks; don't store */
-    } else {
+
+        /*
+         * Append - combine new and old record into single one. Here it's
+         * atomic and thread-safe.
+         */
+
+        if (comm == NREAD_APPEND || comm == NREAD_PREPEND) {
+
+            /* we have it and old_it here - alloc memory to hold both */
+            /* flags was already lost - so recover them from ITEM_suffix(it) */
+
+            flags = (int) strtol(ITEM_suffix(it), (char **) NULL, 10);
+
+            new_it = do_item_alloc(key, it->nkey, flags, it->exptime, it->nbytes + old_it->nbytes - 2 /* CRLF */);
+
+            if (new_it == NULL) {
+                /* SERVER_ERROR out of memory */
+                return 0;
+            }
+
+            /* copy data from it and old_it to new_it */
+
+            if (comm == NREAD_APPEND) {
+                memcpy(ITEM_data(new_it), ITEM_data(old_it), old_it->nbytes);
+                memcpy(ITEM_data(new_it) + old_it->nbytes - 2 /* CRLF */, ITEM_data(it), it->nbytes);
+            } else {
+                /* NREAD_PREPEND */ 
+                memcpy(ITEM_data(new_it), ITEM_data(it), it->nbytes);
+                memcpy(ITEM_data(new_it) + it->nbytes - 2 /* CRLF */, ITEM_data(old_it), old_it->nbytes);
+            }
+
+            it = new_it;
+        }
+
-        /* "set" commands can override the delete lock
-           window... in which case we have to find the old hidden item
@@ -743 +784 @@
-    }
-
-
+ != NULL
-        do_item_remove(old_it);         /* release our reference */
+    if (new_it != NULL)
+        do_item_remove(new_it);
+
-    return stored;
-}
@@ -1209 +1253 @@
-    }
-
-    /* Check if append -- if yes, search for previous entry, and allocate memory for both */
-    if( comm == NREAD_APPEND ){
-       old_it = assoc_find(key,nkey);
-
-       if( old_it && (old_it->nbytes)>2 ){ // previous must be more than \r\n
-          old_vlen = old_it->nbytes - 2;
-          vlen += old_vlen;                // append the length of old data
-       } else {
-          comm = NREAD_REPLACE;            // no old entry: treat as replace
-       }
-    }
-
-    it = item_alloc(key, nkey, flags, realtime(exptime), vlen+2);
-
@@ -1269 +1301 @@
-    c->ritem = ITEM_data(it);
-    c->rlbytes = it->nbytes;
-
-
-    /* If append, prepend old data before new - adjust item, rlbytes variables too
-     * Now that data has been merged, treat simply as a replace command
-     */
-    if (comm == NREAD_APPEND ){
-       memcpy( c->ritem, ITEM_data(old_it), old_vlen );
-       c->ritem += old_vlen;
-       c->rlbytes -= old_vlen;
-       comm = NREAD_REPLACE;
-    }
-
-    c->item_comm = comm;
-    conn_set_state(c, conn_nread);
@@ -1515 +1535 @@
-                (strcmp(tokens[COMMAND_TOKEN].value, "set") == 0 && (comm = NREAD_SET)) ||
-                (strcmp(tokens[COMMAND_TOKEN].value, "replace") == 0 && (comm = NREAD_REPLACE)) ||
+                (strcmp(tokens[COMMAND_TOKEN].value, "prepend") == 0 && (comm = NREAD_PREPEND)) ||
-                (strcmp(tokens[COMMAND_TOKEN].value, "append") == 0 && (comm = NREAD_APPEND)) )) {
-

trunk/server/memcached.h

@@ -139 +139 @@
-#define NREAD_REPLACE 3
-#define NREAD_APPEND 4
+#define NREAD_PREPEND 5
-
-typedef struct {