Supported Functions

TrueAsync adapts 70+ standard PHP functions for non-blocking operation within coroutines. All listed functions automatically become asynchronous when called inside a coroutine. Outside of a coroutine, they work as usual.

DNS

Databases

PDO MySQL

PDO PgSQL

PDO Connection Pooling

Transparent connection pooling for PDO via Async\Pool integration. Each coroutine receives its own connection from the pool with automatic lifecycle management.

MySQLi

PostgreSQL (native)

Each async context uses a separate connection for safe concurrency.

CURL

Sockets

File and Stream I/O

Important: flock() uses the thread pool. The flock() function is a blocking system call that cannot be made non-blocking via libuv I/O events. Inside a coroutine, blocking lock operations (LOCK_SH, LOCK_EX) are offloaded to the libuv thread pool, allowing other coroutines to continue executing while waiting for the lock. Non-blocking locks (LOCK_NB) and unlocks (LOCK_UN) execute directly without the thread pool.

Important: Timeouts for files and pipe streams. PHP does not natively support timeouts for file and pipe stream read/write operations — standard fread(), fwrite() and other functions can block indefinitely. TrueAsync solves this: if a timeout is set for a stream (via stream_set_timeout()), the read operation registers both an IO event and a timer simultaneously. If the timer fires before the IO completes, the read is cancelled and the coroutine receives a result of -1 (indicating a timeout). This only works inside coroutines — outside coroutines, behavior remains standard.

Stream Sockets

Limitation: stream_select() with pipe streams (e.g. from proc_open()) is not supported on Windows. On Linux/macOS it works natively through the event loop.

Process Execution

Important: proc_close() and pclose() block the coroutine. Calling proc_close() or pclose() waits for the child process to exit. Inside a coroutine, this blocks the current coroutine until the process exits — other coroutines continue running. The same happens on implicit calls via destructors: if a variable holding a process resource goes out of scope or is destroyed by the garbage collector, the destructor calls pclose(), which blocks the coroutine where garbage collection is running.

Recommendation: always close processes explicitly via proc_close() instead of relying on destructors, so you can control which coroutine will be blocked.

Timers and Delays

Output Buffering

Each coroutine receives an isolated output buffer.

Not Yet Supported

Functions planned for implementation or not yet adapted.

DNS

Databases

File Operations (metadata)

Note: File metadata operations on local disk complete in microseconds. Making them async only makes sense for network file systems (NFS).

What’s Next?

• spawn() — creating coroutines
• await() — waiting for results
• Coroutines — concepts and examples