Changeset a57c5d

Timestamp:

03/05/08 14:27:59 (4 years ago)

Author:

Tomash Brechko <tomash.brechko@…>

Branches:

master, ketama-compat

Children:

6ab120

Parents:

ed67ff

git-author:

Tomash Brechko <tomash.brechko@…> (03/05/08 14:27:59)

git-committer:

Tomash Brechko <tomash.brechko@…> (03/05/08 14:27:59)

Message:

Add hash_namespace parameter.

The test t/hash_namespace.t is not added to MANIFEST intentionally.

Files:

• Fast.xs (modified) (1 diff)
• lib/Cache/Memcached/Fast.pm (modified) (3 diffs)
• src/client.c (modified) (6 diffs)
• src/client.h (modified) (1 diff)
• src/dispatch_key.c (modified) (5 diffs)
• src/dispatch_key.h (modified) (3 diffs)
• t/hash_namespace.t (added)

Fast.xs

@@ -282 +282 @@
   if (ps && SvOK(*ps))
     client_set_nowait(c, SvTRUE(*ps));
+
+  ps = hv_fetch(conf, "hash_namespace", 14, 0);
+  if (ps && SvOK(*ps))
+    client_set_hash_namespace(c, SvTRUE(*ps));
 
   parse_compress(memd, conf);

lib/Cache/Memcached/Fast.pm

@@ -42 +42 @@
       ketama_points => 150,
       nowait => 1,
+      hash_namespace => 1,
       serialize_methods => [ \&Storable::freeze, \&Storable::thaw ],
       utf8 => ($^V ge v5.8.1 ? 1 : 0),
@@ -186 +187 @@
 to the B<memcached> server.  By using different namespaces clients
 avoid interference with each other.
+
+
+=item I<hash_namespace>
+
+  hash_namespace => 1
+  (default: disabled)
+
+The value is a boolean which enables (true) or disables (false) the
+hashing of the namespace key prefix.  By default for compatibility
+with B<Cache::Memcached> namespace prefix is not hashed along with the
+key.  Thus
+
+  namespace => 'prefix/',
+  ...
+  $memd->set('key', $val);
+
+may use different B<memcached> server than
+
+  namespace => '',
+  ...
+  $memd->set('prefix/key', $val);
+
+because hash values of I<'key'> and I<'prefix/key'> may be different.
+
+However sometimes is it necessary to hash the namespace prefix, for
+instance for interoperability with other clients that do not have the
+notion of the namespace.  When I<hash_namespace> is enabled, both
+examples above will use the same server, the one that I<'prefix/key'>
+is mapped to.  Note that there's no performance penalty then, as
+namespace prefix is hashed only once.  See L</namespace>.
 
 
@@ -446 +477 @@
     namespace => 1,
     nowait => 1,
+    hash_namespace => 1,
     connect_timeout => 1,
     io_timeout => 1,

src/client.c

@@ -27 +27 @@
 #include "parse_keyword.h"
 #include "dispatch_key.h"
+#include "compute_crc32.h"
 #include <stdlib.h>
 #include <unistd.h>
@@ -256 +257 @@
   int close_on_error;
   int nowait;
+  int hash_namespace;
 
   struct array index_list;
@@ -352 +354 @@
   c->close_on_error = 1;
   c->nowait = 0;
+  c->hash_namespace = 0;
 
   c->generation = 1;            /* Different from initial command state.  */
@@ -442 +445 @@
 {
   c->nowait = enable;
+}
+
+
+void
+client_set_hash_namespace(struct client *c, int enable)
+{
+  c->hash_namespace = enable;
 }
 
@@ -487 +497 @@
           c->prefix_len = 1;
         }
+
+      if (c->hash_namespace)
+        dispatch_set_prefix_crc32(&c->dispatch, 0x0U);
+
       return MEMCACHED_SUCCESS;
     }
@@ -502 +516 @@
   c->prefix = s;
   c->prefix_len = 1 + ns_len;
+
+  if (c->hash_namespace)
+    dispatch_set_prefix_crc32(&c->dispatch, compute_crc32(ns, ns_len));
 
   return MEMCACHED_SUCCESS;

src/client.h

@@ -144 +144 @@
 extern
 void
+client_set_hash_namespace(struct client *c, int enable);
+
+extern
+void
 client_reset(struct client *c, struct result_object *o, int noreply);
 

src/dispatch_key.c

@@ -1 +1 @@
 /*
-  Copyright (C) 2007 Tomash Brechko.  All rights reserved.
+  Copyright (C) 2007-2008 Tomash Brechko.  All rights reserved.
 
   When used to build Perl module:
@@ -120 +120 @@
   */
   struct continuum_point *p;
-  unsigned int crc32 = compute_crc32(key, key_len);
+  unsigned int crc32 = compute_crc32_add(state->prefix_crc32, key, key_len);
   unsigned int hash = ((crc32 >> 16) & 0x00007fff);
   unsigned int point = hash % (unsigned int) (state->total_weight + 0.5);
@@ -223 +223 @@
                         const char *key, size_t key_len)
 {
-  unsigned int point = compute_crc32(key, key_len);
+  unsigned int point = compute_crc32_add(state->prefix_crc32, key, key_len);
   struct continuum_point *p = dispatch_find_bucket(state, point);
   return p->index;
@@ -235 +235 @@
   state->total_weight = 0.0;
   state->ketama_points = 0;
+  state->prefix_crc32 = 0x0U;
 }
 
@@ -249 +250 @@
 {
   state->ketama_points = ketama_points;
+}
+
+
+void
+dispatch_set_prefix_crc32(struct dispatch_state *state, unsigned int crc32)
+{
+  state->prefix_crc32 = crc32;
 }
 

src/dispatch_key.h

@@ -1 +1 @@
 /*
-  Copyright (C) 2007 Tomash Brechko.  All rights reserved.
+  Copyright (C) 2007-2008 Tomash Brechko.  All rights reserved.
 
   When used to build Perl module:
@@ -34 +34 @@
   double total_weight;
   int ketama_points;
+  unsigned int prefix_crc32;
 };
 
@@ -50 +51 @@
 
 extern
+void
+dispatch_set_prefix_crc32(struct dispatch_state *state, unsigned int crc32);
+
+extern
 int
 dispatch_add_server(struct dispatch_state *state,