Changeset 615

Timestamp:

10/03/07 19:59:11 (1 year ago)

Author:

plindner

Message:

Incorporate "cas" operation developed by Dustin Sallings
<dustin@spy.net> and implemented by Chris Goffinet
<goffinet@yahoo-inc.com>. This change allows you to do
atomic changes to an existing key.

Files:

• trunk/server/ChangeLog (modified) (1 diff)
• trunk/server/doc/protocol.txt (modified) (8 diffs)
• trunk/server/memcached.c (modified) (9 diffs)
• trunk/server/t/getset.t (modified) (2 diffs)

trunk/server/ChangeLog

@@ +1 @@
+2007-10-03 Paul Lindner <lindner@inuus.com>
+        * Incorporate "cas" operation developed by Dustin
+          Sallings <dustin@spy.net> and implemented by
+          Chris Goffinet <goffinet@yahoo-inc.com>.  This
+          change allows you to do atomic changes to an
+          existing key.
+
-2007-08-21 Paul Lindner <lindner@inuus.com>
-        * Incorporate incrememnt patch from Evan Miller 

trunk/server/doc/protocol.txt

@@ -54 +54 @@
-There are three types of commands. 
-
-three: "set", "add" and "replace") ask the
-
-
-
-
-is only one: "get
+four: "set", "add", "replace", and "cas")
+
+
+expects one 
+
+are two: "get" and "gets
-retrieve data corresponding to a set of keys (one or more keys in one
-request). The client sends a command line, which includes all the
@@ -126 +126 @@
-First, the client sends a command line which looks like this:
-
-
-
- or "replace
+ [<unqiue>]
+
+, "replace", or "cas
-
-  "set" means "store this data".  
@@ -137 +137 @@
-  "replace" means "store this data, but only if the server *does*
-  already hold data for this key".
+
+  "cas" is a check and set operation which means "store this data but
+  only if no one else has updated since I last fetched it."
-
-- <key> is the key under which the client asks to store the data
@@ -159 +162 @@
-  it's followed by an empty data block).
-
+- <cas unique> is a unique 64-bit value of an existing entry.
+
-After this line, the client sends the data block:
-
@@ -176 +181 @@
-item is in a delete queue (see the "delete" command below).
-
+- "EXISTS\r\n" to indicate that the item you are trying to store with
+a "cas" command has been modified since you last fetched it.
-
-Retrieval command:
-------------------
-
- look
+s "get" and "gets" operate
-
-get <key>*\r\n
+gets <key>*\r\n
-
-- <key>* means one or more key strings separated by whitespace.
@@ -196 +204 @@
-Each item sent by the server looks like this:
-
-
+ [<cas unique>]
-<data block>\r\n
-
@@ -205 +213 @@
-- <bytes> is the length of the data block to follow, *not* including
-  its delimiting \r\n
+
+- <cas unique> is a unique 64-bit integer that uniquely identifies
+  this specific item.
-
-- <data block> is the data for this item.
@@ -213 +224 @@
-but deleted to make space for more items, or expired, or explicitly
-deleted by a client).
-
-
-

trunk/server/memcached.c

@@ -1026 +1026 @@
-
-/* ntokens is overwritten here... shrug.. */
-
+, bool return_key_ptr
-    char *key;
-    size_t nkey;
@@ -1032 +1032 @@
-    item *it;
-    token_t *key_token = &tokens[KEY_TOKEN];
-
+
+
-    assert(c != NULL);
-
@@ -1082 +1083 @@
-                 *   " " + flags + " " + data length + "\r\n" + data (with \r\n)
-                 */
-
-
-
-
-
-
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
-                if (settings.verbose > 1)
-                    fprintf(stderr, ">%d sending key %s\n", c->sfd, ITEM_key(it));
@@ -1136 +1155 @@
-}
-
-
+, bool handle_cas
-    char *key;
-    size_t nkey;
@@ -1142 +1161 @@
-    time_t exptime;
-    int vlen;
+    uint32_t req_memory_ptr, in_memory_ptr;
+
-    item *it;
-
@@ -1157 +1178 @@
-    exptime = strtol(tokens[3].value, NULL, 10);
-    vlen = strtol(tokens[4].value, NULL, 10);
+
+    // does cas value exist?
+    if(tokens[5].value)
+    {
+      req_memory_ptr = strtoull(tokens[5].value, NULL, 10);
+    }
-
-    if(errno == ERANGE || ((flags == 0 || exptime == 0) && errno == EINVAL)) {
@@ -1181 +1208 @@
-
-    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) {
@@ -1420 +1479 @@
-
-    ntokens = tokenize_command(command, tokens, MAX_TOKENS);
-
-    if (ntokens >= 3 &&
-        ((strcmp(tokens[COMMAND_TOKEN].value, "get") == 0) ||
-         (strcmp(tokens[COMMAND_TOKEN].value, "bget") == 0))) {
-
-
+, false
-
-    } else if (ntokens == 6 &&
@@ -1432 +1490 @@
-                (strcmp(tokens[COMMAND_TOKEN].value, "replace") == 0 && (comm = NREAD_REPLACE)))) {
-
-
+
+
+
+
+
-
-    } else if (ntokens == 4 && (strcmp(tokens[COMMAND_TOKEN].value, "incr") == 0)) {
-
-        process_arithmetic_command(c, tokens, ntokens, 1);
+
+    } else if (ntokens >= 3 && (strcmp(tokens[COMMAND_TOKEN].value, "gets") == 0)) {
+
+        process_get_command(c, tokens, ntokens, true);
-
-    } else if (ntokens == 4 && (strcmp(tokens[COMMAND_TOKEN].value, "decr") == 0)) {

trunk/server/t/getset.t

@@ -2 +2 @@
-
-use strict;
-28
+35
-use FindBin qw($Bin);
-use lib "$Bin/lib";
@@ -43 +43 @@
-is(scalar <$sock>, "NOT_FOUND\r\n", "deleted foo, but not found");
-
+# add moo
+#
+print $sock "add moo 0 0 6\r\nmooval\r\n";
+is(scalar <$sock>, "STORED\r\n", "stored barval");
+mem_get_is($sock, "moo", "mooval");
+
+# check-and-set (cas) failure case, try to set value with incorrect cas unique val
+print $sock "cas moo 0 0 6 0\r\nMOOVAL\r\n";
+is(scalar <$sock>, "EXISTS\r\n", "check and set with invalid id");
+
+# test "gets", grab unique ID
+print $sock "gets moo\r\n";
+# VALUE moo 0 6 3084947704
+# 
+my @retvals = split(/ /, scalar <$sock>);
+my $data = scalar <$sock>; # grab data
+my $dot  = scalar <$sock>; # grab dot on line by itself
+is($retvals[0], "VALUE", "get value using 'gets'");
+my $unique_id = $retvals[4];
+# clean off \r\n
+$unique_id =~ s/\r\n$//;
+ok($unique_id =~ /^\d+$/, "unique ID '$unique_id' is an integer");
+# now test that we can store moo with the correct unique id
+print $sock "cas moo 0 0 6 $unique_id\r\nMOOVAL\r\n";
+is(scalar <$sock>, "STORED\r\n");
+mem_get_is($sock, "moo", "MOOVAL");
+
-# pipeling is okay
-print $sock "set foo 0 0 6\r\nfooval\r\ndelete foo\r\nset foo 0 0 6\r\nfooval\r\ndelete foo\r\n";