Added randomized read behavior
[m6w6/libmemcached] / libmemcached / memcached_get.c
index a7bf3a963b8f4b422f38595176321a85bf8bab58..6c730093c9cd14d8407b36f7f6a2b6d45c15f551 100644 (file)
@@ -14,6 +14,14 @@ char *memcached_get(memcached_st *ptr, const char *key,
                               flags, error);
 }
 
+static memcached_return memcached_mget_by_key_real(memcached_st *ptr, 
+                                                   const char *master_key, 
+                                                   size_t master_key_length,
+                                                   const char * const *keys, 
+                                                   const size_t *key_length, 
+                                                   size_t number_of_keys,
+                                                   bool mget_mode);
+
 char *memcached_get_by_key(memcached_st *ptr, 
                            const char *master_key, 
                            size_t master_key_length, 
@@ -27,11 +35,16 @@ char *memcached_get_by_key(memcached_st *ptr,
   uint32_t dummy_flags;
   memcached_return dummy_error;
 
+  unlikely (ptr->flags & MEM_USE_UDP)
+  {
+    *error= MEMCACHED_NOT_SUPPORTED;
+    return NULL;
+  }
+
   /* Request the key */
-  *error= memcached_mget_by_key(ptr, 
-                                master_key, 
-                                master_key_length, 
-                                (char **)&key, &key_length, 1);
+  *error= memcached_mget_by_key_real(ptr, master_key, master_key_length, 
+                                     (const char * const *)&key, 
+                                     &key_length, 1, false);
 
   value= memcached_fetch(ptr, NULL, NULL, 
                          value_length, flags, error);
@@ -53,7 +66,7 @@ char *memcached_get_by_key(memcached_st *ptr,
       {
         if (rc == MEMCACHED_BUFFERED)
         {
-          uint8_t latch; /* We use latch to track the state of the original socket */
+          uint64_t latch; /* We use latch to track the state of the original socket */
           latch= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_BUFFER_REQUESTS);
           if (latch == 0)
             memcached_behavior_set(ptr, MEMCACHED_BEHAVIOR_BUFFER_REQUESTS, 1);
@@ -96,29 +109,38 @@ char *memcached_get_by_key(memcached_st *ptr,
 }
 
 memcached_return memcached_mget(memcached_st *ptr, 
-                                char **keys, size_t *key_length, 
-                                unsigned int number_of_keys)
+                                const char * const *keys, 
+                                const size_t *key_length, 
+                                size_t number_of_keys)
 {
   return memcached_mget_by_key(ptr, NULL, 0, keys, key_length, number_of_keys);
 }
 
 static memcached_return binary_mget_by_key(memcached_st *ptr,
                                            unsigned int master_server_key,
-                                           char **keys, size_t *key_length,
-                                           unsigned int number_of_keys);
-
-memcached_return memcached_mget_by_key(memcached_st *ptr, 
-                                       const char *master_key, 
-                                       size_t master_key_length,
-                                       char **keys, 
-                                       size_t *key_length, 
-                                       unsigned int number_of_keys)
+                                           bool is_master_key_set,
+                                           const char * const *keys, 
+                                           const size_t *key_length,
+                                           size_t number_of_keys,
+                                          bool mget_mode);
+
+static memcached_return memcached_mget_by_key_real(memcached_st *ptr, 
+                                                   const char *master_key, 
+                                                   size_t master_key_length,
+                                                   const char * const *keys, 
+                                                   const size_t *key_length, 
+                                                   size_t number_of_keys,
+                                                   bool mget_mode)
 {
   unsigned int x;
   memcached_return rc= MEMCACHED_NOTFOUND;
-  char *get_command= "get ";
+  const char *get_command= "get ";
   uint8_t get_command_length= 4;
-  unsigned int master_server_key= 0;
+  unsigned int master_server_key= (unsigned int)-1; /* 0 is a valid server id! */
+  bool is_master_key_set= false;
+
+   unlikely (ptr->flags & MEM_USE_UDP)
+    return MEMCACHED_NOT_SUPPORTED;
 
   LIBMEMCACHED_MEMCACHED_MGET_START();
   ptr->cursor_server= 0;
@@ -129,20 +151,15 @@ memcached_return memcached_mget_by_key(memcached_st *ptr,
   if (ptr->number_of_hosts == 0)
     return MEMCACHED_NO_SERVERS;
 
-  if ((ptr->flags & MEM_VERIFY_KEY) && (memcachd_key_test(keys, key_length, number_of_keys) == MEMCACHED_BAD_KEY_PROVIDED))
+  if ((ptr->flags & MEM_VERIFY_KEY) && (memcached_key_test(keys, key_length, number_of_keys) == MEMCACHED_BAD_KEY_PROVIDED))
     return MEMCACHED_BAD_KEY_PROVIDED;
 
-  if (ptr->flags & MEM_SUPPORT_CAS)
-  {
-    get_command= "gets ";
-    get_command_length= 5;
-  }
-
   if (master_key && master_key_length)
   {
-    if ((ptr->flags & MEM_VERIFY_KEY) && (memcachd_key_test((char **)&master_key, &master_key_length, 1) == MEMCACHED_BAD_KEY_PROVIDED))
+    if ((ptr->flags & MEM_VERIFY_KEY) && (memcached_key_test((const char * const *)&master_key, &master_key_length, 1) == MEMCACHED_BAD_KEY_PROVIDED))
       return MEMCACHED_BAD_KEY_PROVIDED;
     master_server_key= memcached_generate_hash(ptr, master_key, master_key_length);
+    is_master_key_set= true;
   }
 
   /* 
@@ -166,8 +183,14 @@ memcached_return memcached_mget_by_key(memcached_st *ptr,
   }
   
   if (ptr->flags & MEM_BINARY_PROTOCOL)
-    return binary_mget_by_key(ptr, master_server_key, keys, 
-                              key_length, number_of_keys);
+    return binary_mget_by_key(ptr, master_server_key, is_master_key_set, keys, 
+                              key_length, number_of_keys, mget_mode);
+
+  if (ptr->flags & MEM_SUPPORT_CAS)
+  {
+    get_command= "gets ";
+    get_command_length= 5;
+  }
 
   /* 
     If a server fails we warn about errors and start all over with sending keys
@@ -177,7 +200,7 @@ memcached_return memcached_mget_by_key(memcached_st *ptr,
   {
     unsigned int server_key;
 
-    if (master_server_key)
+    if (is_master_key_set)
       server_key= master_server_key;
     else
       server_key= memcached_generate_hash(ptr, keys[x], key_length[x]);
@@ -244,10 +267,64 @@ memcached_return memcached_mget_by_key(memcached_st *ptr,
   return rc;
 }
 
-static memcached_return binary_mget_by_key(memcached_st *ptr, 
+memcached_return memcached_mget_by_key(memcached_st *ptr, 
+                                       const char *master_key, 
+                                       size_t master_key_length,
+                                       const char * const *keys, 
+                                       const size_t *key_length, 
+                                       size_t number_of_keys)
+{
+  return memcached_mget_by_key_real(ptr, master_key, master_key_length, keys, 
+                                    key_length, number_of_keys, true);
+}
+
+memcached_return memcached_mget_execute(memcached_st *ptr,
+                                        const char * const *keys,
+                                        const size_t *key_length,
+                                        size_t number_of_keys,
+                                        memcached_execute_function *callback,
+                                        void *context,
+                                        unsigned int number_of_callbacks)
+{
+  return memcached_mget_execute_by_key(ptr, NULL, 0, keys, key_length,
+                                       number_of_keys, callback,
+                                       context, number_of_callbacks);
+}
+
+memcached_return memcached_mget_execute_by_key(memcached_st *ptr,
+                                               const char *master_key,
+                                               size_t master_key_length,
+                                               const char * const *keys,
+                                               const size_t *key_length,
+                                               size_t number_of_keys,
+                                               memcached_execute_function *callback,
+                                               void *context,
+                                               unsigned int number_of_callbacks)
+{
+  if ((ptr->flags & MEM_BINARY_PROTOCOL) == 0)
+    return MEMCACHED_NOT_SUPPORTED;
+
+  memcached_return rc;
+  memcached_callback_st *original_callbacks= ptr->callbacks;
+  memcached_callback_st cb= {
+    .callback= callback,
+    .context= context,
+    .number_of_callback= number_of_callbacks
+  };
+
+  ptr->callbacks= &cb;
+  rc= memcached_mget_by_key(ptr, master_key, master_key_length, keys,
+                            key_length, number_of_keys);
+  ptr->callbacks= original_callbacks;
+  return rc;
+}
+
+static memcached_return simple_binary_mget(memcached_st *ptr,
                                            unsigned int master_server_key,
-                                           char **keys, size_t *key_length, 
-                                           unsigned int number_of_keys)
+                                           bool is_master_key_set,
+                                           const char * const *keys, 
+                                           const size_t *key_length, 
+                                           size_t number_of_keys, bool mget_mode)
 {
   memcached_return rc= MEMCACHED_NOTFOUND;
   uint32_t x;
@@ -262,7 +339,7 @@ static memcached_return binary_mget_by_key(memcached_st *ptr,
   {
     unsigned int server_key;
 
-    if (master_server_key)
+    if (is_master_key_set)
       server_key= master_server_key;
     else
       server_key= memcached_generate_hash(ptr, keys[x], key_length[x]);
@@ -276,37 +353,44 @@ static memcached_return binary_mget_by_key(memcached_st *ptr,
      
     protocol_binary_request_getk request= {.bytes= {0}};
     request.message.header.request.magic= PROTOCOL_BINARY_REQ;
-    if (number_of_keys == 1)
-      request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETK;
-    else
+    if (mget_mode)
       request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETKQ;
+    else
+      request.message.header.request.opcode= PROTOCOL_BINARY_CMD_GETK;
 
     memcached_return vk;
     vk= memcached_validate_key_length(key_length[x],
                                       ptr->flags & MEM_BINARY_PROTOCOL);
-    unlikely (vk != MEMCACHED_SUCCESS) {
+    unlikely (vk != MEMCACHED_SUCCESS)
+    {
       if (x > 0)
-        memcached_io_reset(ptr);
+        memcached_io_reset(&ptr->hosts[server_key]);
       return vk;
     }
 
     request.message.header.request.keylen= htons((uint16_t)key_length[x]);
     request.message.header.request.datatype= PROTOCOL_BINARY_RAW_BYTES;
-    request.message.header.request.bodylen= htonl(key_length[x]);
+    request.message.header.request.bodylen= htonl((uint32_t) key_length[x]);
     
     if ((memcached_io_write(&ptr->hosts[server_key], request.bytes,
                             sizeof(request.bytes), 0) == -1) ||
         (memcached_io_write(&ptr->hosts[server_key], keys[x], 
-                            key_length[x], flush) == -1)) 
+                            key_length[x], (char) flush) == -1)) 
     {
       memcached_server_response_reset(&ptr->hosts[server_key]);
       rc= MEMCACHED_SOME_ERRORS;
       continue;
     }
+    
+    /* We just want one pending response per server */
+    memcached_server_response_reset(&ptr->hosts[server_key]); 
     memcached_server_response_increment(&ptr->hosts[server_key]);    
+    if ((x > 0 && x == ptr->io_key_prefetch) &&
+        memcached_flush_buffers(ptr) != MEMCACHED_SUCCESS)
+      rc= MEMCACHED_SOME_ERRORS;
   }
 
-  if (number_of_keys > 1
+  if (mget_mode
   {
     /*
      * Send a noop command to flush the buffers
@@ -333,10 +417,155 @@ static memcached_return binary_mget_by_key(memcached_st *ptr,
           memcached_io_reset(&ptr->hosts[x]);
           rc= MEMCACHED_SOME_ERRORS;
         }
-        memcached_server_response_increment(&ptr->hosts[x]);    
       }
     }
 
 
   return rc;
 }
+
+static memcached_return replication_binary_mget(memcached_st *ptr,
+                                                uint32_t* hash, 
+                                                bool* dead_servers,
+                                                const char *const *keys, 
+                                                const size_t *key_length,
+                                                size_t number_of_keys)
+{
+  memcached_return rc= MEMCACHED_NOTFOUND;
+  uint32_t x, start = 0;
+  uint64_t randomize_read = memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_RANDOMIZE_REPLICA_READ);
+
+  if (randomize_read) {
+    srandom((uint32_t) time(NULL));
+    start = (uint32_t)(random() % (ptr->number_of_replicas + 1));
+  }
+
+  /* Loop for each replica */
+  for (uint32_t replica= 0; replica <= ptr->number_of_replicas; ++replica)
+  {
+    bool success= true;
+    for (x= 0; x < number_of_keys; ++x)
+    {
+      uint32_t server;
+      
+      if (hash[x] == ptr->number_of_hosts)
+        continue; /* Already successfully sent */
+
+      server= hash[x] + replica;
+
+      /* In case of randomized reads */
+      if (randomize_read) {
+        if ((server + start) <= (hash[x] + ptr->number_of_replicas)) {
+          server += start;
+        }
+      }
+      
+      while (server >= ptr->number_of_hosts)
+        server -= ptr->number_of_hosts;
+
+      if (dead_servers[server])
+        continue;
+
+      if (memcached_server_response_count(&ptr->hosts[server]) == 0)
+      {
+        rc= memcached_connect(&ptr->hosts[server]);
+        if (rc != MEMCACHED_SUCCESS)
+        {
+          memcached_io_reset(&ptr->hosts[server]);
+          dead_servers[server]= true;
+          success= false;
+          continue;
+        }
+      }
+
+      protocol_binary_request_getk request= {
+        .message.header.request= {
+          .magic= PROTOCOL_BINARY_REQ,
+          .opcode= PROTOCOL_BINARY_CMD_GETK,
+          .keylen= htons((uint16_t)key_length[x]),
+          .datatype= PROTOCOL_BINARY_RAW_BYTES,
+          .bodylen= htonl((uint32_t)key_length[x])
+        }
+      };
+
+      /*
+       * We need to disable buffering to actually know that the request was
+       * successfully sent to the server (so that we should expect a result
+       * back). It would be nice to do this in buffered mode, but then it
+       * would be complex to handle all error situations if we got to send
+       * some of the messages, and then we failed on writing out some others
+       * and we used the callback interface from memcached_mget_execute so
+       * that we might have processed some of the responses etc. For now,
+       * just make sure we work _correctly_
+       */
+      if ((memcached_io_write(&ptr->hosts[server], request.bytes,
+                              sizeof(request.bytes), 0) == -1) ||
+          (memcached_io_write(&ptr->hosts[server], keys[x],
+                              key_length[x], 1) == -1))
+      {
+        memcached_io_reset(&ptr->hosts[server]);
+        dead_servers[server]= true;
+        success= false;
+        continue;
+      }
+
+      memcached_server_response_increment(&ptr->hosts[server]);
+      hash[x]= ptr->number_of_hosts;
+    }
+
+    if (success)
+      break;
+  }
+
+  return rc;
+}
+
+static memcached_return binary_mget_by_key(memcached_st *ptr,
+                                           unsigned int master_server_key,
+                                           bool is_master_key_set,
+                                           const char * const *keys, 
+                                           const size_t *key_length,
+                                           size_t number_of_keys, 
+                                           bool mget_mode)
+{
+  memcached_return rc;
+
+  if (ptr->number_of_replicas == 0) 
+  {
+    rc= simple_binary_mget(ptr, master_server_key, is_master_key_set,
+                           keys, key_length, number_of_keys, mget_mode);
+  } 
+  else 
+  {
+    uint32_t* hash;
+    bool* dead_servers;
+
+    hash= ptr->call_malloc(ptr, sizeof(uint32_t) * number_of_keys);
+    dead_servers= ptr->call_calloc(ptr, ptr->number_of_hosts, sizeof(bool));
+
+    if (hash == NULL || dead_servers == NULL)
+    {
+      ptr->call_free(ptr, hash);
+      ptr->call_free(ptr, dead_servers);
+      return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
+    }
+
+    if (is_master_key_set)
+      for (unsigned int x= 0; x < number_of_keys; x++)
+        hash[x]= master_server_key;
+    else
+      for (unsigned int x= 0; x < number_of_keys; x++)
+        hash[x]= memcached_generate_hash(ptr, keys[x], key_length[x]);
+
+    rc= replication_binary_mget(ptr, hash, dead_servers, keys, 
+                                key_length, number_of_keys);
+
+    ptr->call_free(ptr, hash);
+    ptr->call_free(ptr, dead_servers);
+
+    return MEMCACHED_SUCCESS;
+  }
+
+  return rc;
+}