StdoutLock

StdoutLock is a type in Rust's standard library that represents a locked handle to the program’s standard output. It is obtained by calling std::io::stdout().lock(), which acquires an internal mutex around the shared stdout. While the lock is held, writes performed via the StdoutLock are serialized with respect to other potential writers to stdout, preventing interleaving of output from multiple threads.

StdoutLock implements the Write trait, so you can use the usual write!, writeln!, and related macros with it. The guard is released when the StdoutLock is dropped, at which point the underlying lock is released and buffered data may be flushed. This makes it convenient to bundle multiple writes under a single lock.

Lifetime-wise, StdoutLock<'a> borrows from the Stdout handle and cannot outlive it. A common pattern is to obtain a lock for a scope and perform several writes before dropping it. This provides thread-safe access to stdout without requiring per-write locking.

Performance and correctness: locking stdout once for a group of writes can be more efficient than locking for every single write, especially in multithreaded programs. However, holding the lock for long operations can cause other threads to block, so the lock scope should be kept reasonably short and focused.

Error handling: writes through a StdoutLock return a Result, allowing callers to unwrap or propagate errors as needed. StdoutLock is a thin synchronization wrapper around the standard output, ensuring safe, serialized access across threads while preserving familiar Write-based idioms.