XInitThreads(3)

💅 XInitThreads(3) — XLIB FUNCTIONS ✨

okay so bestie, this is the Xlib multi-threading support page, and she slays. The NAME list is XInitThreads, XLockDisplay, and XUnlockDisplay, but XFreeThreads also shows up in the SYNTAX and DESCRIPTION — not me noticing the plot twist and refusing to skip her. 🫶

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✨ NAME ✨

• XInitThreads, XLockDisplay, XUnlockDisplay — multi-threading support

Lowkey yes, XFreeThreads is in the SYNTAX and DESCRIPTION even though the NAME list is shorter. Keep reading, iykyk. 💀

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🛠 SYNTAX 🛠

Status XInitThreads(void);

Status XFreeThreads(void);

void XLockDisplay(Display *display);

void XUnlockDisplay(Display *display);

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🌸 ARGUMENTS 🌸

• display — specifies the connection to the X server. That's the whole argument, and she is iconic.

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💖 DESCRIPTION 💖

Okay so XInitThreads is the main character here: it initializes Xlib support for concurrent threads. Highkey, the rule is strict, bestie — this function must be the first Xlib function a multi-threaded program calls, and it must complete before any other Xlib call is made. No sneaky side quests before this. 🚨

It returns a nonzero status if initialization was successful; otherwise, it returns zero. On systems that do not support threads, this function always returns zero. Periodt.

It is only necessary to call this function if multiple threads might use Xlib concurrently. If all calls to Xlib functions are protected by some other access mechanism (for example, a mutual exclusion lock in a toolkit or through explicit client programming), Xlib thread initialization is not required. It is recommended that single-threaded programs not call this function. So if you're single-threaded, no cap, skip it.

XFreeThreads frees the memory allocated by XInitThreads. She's the cleanup bestie. 🧚

XLockDisplay locks out all other threads from using the specified display. Other threads attempting to use the display will block until the display is unlocked by this thread. Nested calls to XLockDisplay work correctly; the display will not actually be unlocked until XUnlockDisplay has been called the same number of times as XLockDisplay. This function has no effect unless Xlib was successfully initialized for threads using XInitThreads. So don't expect lock magic if you didn't do the init. 💅

XUnlockDisplay allows other threads to use the specified display again. Any threads that have blocked on the display are allowed to continue. Nested locking works correctly; if XLockDisplay has been called multiple times by a thread, then XUnlockDisplay must be called an equal number of times before the display is actually unlocked. This function has no effect unless Xlib was successfully initialized for threads using XInitThreads. Matching lock/unlock counts are the vibe check. ✅

Fr fr, those “has no effect unless…” caveats are the whole game — successful XInitThreads first, or the lock/unlock functions are just there looking pretty. I’m obsessed with the Drama of it all. 🎀

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👀 SEE ALSO 👀

• Xlib - C Language X Interface — the classic Xlib reference, go read her.

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X Version 11, libX11 1.8.14 — page XInitThreads(3), and the footer didn’t list a date, so I’m not inventing one. Bye bestie, go initialize those threads first. 💜🦋