set

Note

This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information.

Store a value (replacing if present)

public function set(
  string $key,
  string $value,
  int $flags = 0,
  int $expiration = 0,
): Awaitable<void>;

Parameters

• string $key - Name of the key to store
• string $value - Datum to store
• int $flags = 0
• int $expiration = 0

Returns

• Awaitable<void>

Examples

The following example shows how to use MCRouter::set to set key/value pair to the memcached server. While you cannot MCRouter::add the same key twice, you can reset a value for a given key via set. It is quite possible to always use set instead of add since it is generally superset of functionality, but add can be good if you explicitly want to catch someone trying to set a key to a different value.

If you pass an expiration time for the key, that is in seconds.

And these are the bitwise or style flags that can be passed to set:

MC_MSG_FLAG_PHP_SERIALIZED = 0x1,
MC_MSG_FLAG_COMPRESSED = 0x2,
MC_MSG_FLAG_FB_SERIALIZED = 0x4,
MC_MSG_FLAG_FB_COMPACT_SERIALIZED = 0x8,
MC_MSG_FLAG_ASCII_INT_SERIALIZED = 0x10,
MC_MSG_FLAG_NZLIB_COMPRESSED = 0x800,
MC_MSG_FLAG_QUICKLZ_COMPRESSED = 0x2000,
MC_MSG_FLAG_SNAPPY_COMPRESSED = 0x4000,
MC_MSG_FLAG_BIG_VALUE = 0X8000,
MC_MSG_FLAG_NEGATIVE_CACHE = 0x10000,
MC_MSG_FLAG_HOT_KEY = 0x20000,

See the header file with the flags

function get_simple_mcrouter(): \MCRouter {
  $servers = Vector {\getenv('HHVM_TEST_MCROUTER')};
  $mc = \MCRouter::createSimple($servers);
  return $mc;
}

async function set_value(
  \MCRouter $mc,
  string $key,
  string $value,
): Awaitable<void> {
  // can also pass optional int flags and int expiration time (in seconds)
  await $mc->set($key, $value);
}

<<__EntryPoint>>
async function run(): Awaitable<void> {
  $mc = get_simple_mcrouter();
  $unique_key = \str_shuffle('ABCDEFGHIJKLMN');
  await set_value($mc, $unique_key, "Hi");
  $val = await $mc->get($unique_key);
  \var_dump($val);
  try {
    // Setting the same key again is fine
    await set_value($mc, $unique_key, "Bye");
    $val = await $mc->get($unique_key);
    \var_dump($val);
  } catch (\MCRouterException $ex) {
    \var_dump($ex->getMessage()); // We should not get here
  }
}
```.hhvm.expectf
string(2) "Hi"
string(3) "Bye"
```.example.hhvm.out
string(2) "Hi"
string(3) "Bye"
```.skipif
\Hack\UserDocumentation\API\Examples\MCRouter\skipif();