CPG_ZCB_ALLOC(3)

✨ CPG_ZCB_ALLOC(3) ✨

okay bestie, sit down, we're learning about cpg_zcb_alloc — the zero copy buffer allocator from the Corosync Cluster Engine Programmer's Manual. 🎀 This one is lowkey iconic because it does zero copying, and the way it does that is by asking the operating system to hand over memory in a way the IPC layer can just... point at. No copying. Obsessed. 💅

🌸 NAME 🌸

cpg_zcb_alloc — Allocates a zero copy buffer ✨

🦋 SYNOPSIS 🦋

#include <corosync/cpg.h>

int cpg_zcb_alloc(cpg_handle_t handle, size_t size, void **buffer);

💖 DESCRIPTION 💖

So here's the tea. The cpg_zcb_alloc function allocates a zero copy buffer for use with the cpg_zcb_mcast_joined(3) function. That's its whole job and it does it gorgeously. ✨

⚠️ bestie please read this one — this buffer should not be used in another thread while a cpg_zcb_mcast_joined operation is taking place on the buffer. Like, one thread at a time, okay? Sharing is caring but not here. 😭

The buffer is allocated via operating system mechanisms to avoid copying in the IPC layer. no copy, no drama, no cap. 🧚

Now the arguments, one by one, because we don't skip:

• The argument handle describes the handle on which the buffer will be allocated. 🫶
• The argument size requests a buffer of size be allocated. 📏
• The buffer argument is set to the buffer address that is allocated by this operation. 👑

⭐ RETURN VALUE ⭐

This call returns the CS_OK value if successful, otherwise an error is returned. simple, clean, no notes. 💚

💀 ERRORS 💀

The errors are undocumented.

(yes really. that's the whole section. we move.) 🙈

🌈 SEE ALSO 🌈

Go read the whole friend group, they're all linked up:

• cpg_overview(3), cpg_initialize(3), cpg_finalize(3), cpg_fd_get(3)
• cpg_dispatch(3), cpg_join(3), cpg_leave(3), cpg_mcast_joined(3)
• cpg_membership_get(3) cpg_zcb_alloc(3) cpg_zcb_free(3)
• cpg_zcb_mcast_joined(3) cpg_context_get(3) cpg_context_set(3)
• cpg_local_get(3)

And the error codes, served in the exact order they came in, no edits:

• CS_ERR_TRY_AGAIN — Resource temporarily unavailable
• CS_ERR_INVALID_PARAM — Invalid argument
• CS_ERR_ACCESS — Permission denied
• CS_ERR_LIBRARY — The connection failed
• CS_ERR_INTERRUPT — System call interrupted by a signal
• CS_ERR_NOT_SUPPORTED — The requested protocol/functionality not supported
• CS_ERR_MESSAGE_ERROR — Incorrect auth message received
• CS_ERR_NO_MEMORY — Not enough memory to complete the requested task

and that's the whole page, bestie, you ate that. 💅✨

this lil masterpiece came out of the corosync Man Page on 2009-04-15 — yes she's vintage, yes she still slays, we stan an ageless queen. 👑💖