ARES_CANCEL(3)

okay bestie, welcome to ARES_CANCEL(3) from the Library Functions Manual — the little page that literally says “cancel a resolve” and honestly? iconic 🫶

🎀 NAME 🎀

ares_cancel — cancel a resolve 💅

✨ SYNOPSIS ✨

#include <ares.h>

void ares_cancel(ares_channel_t *channel)

🌸 DESCRIPTION 🌸

So ares_cancel(3) cancels all the lookups/requests made on the name service channel identified by channel. Not some. Not a few. All of them, bestie 😭

When it does that, it invokes the callbacks for each pending query on the channel and passes them a status of ARES_ECANCELLED. This is the whole point: those calls give the callbacks a chance to clean up any state that might have been stored in their arguments. Obsessed with a graceful exit 💖

One tiny but important vibe check: if one of those callback invocations adds a new request to the channel, that request will not be cancelled by the current invocation of ares_cancel(3). New request = new era, it survives this cancel ✨

🔁 REENTRANCY 🔁

A callback invoked by ares_cancel(3) may call c-ares functions on the same channel. Yes, fr fr — and here’s why it’s not chaotic: the channel lock is recursive, and each query is unlinked from the library’s internal structures before its callback runs. So a reentrant call cannot encounter a query that is part-way through being torn down. No half-torn-down query jumpscare 💀

This includes starting new lookups, as described above, and reconfiguring the server list with ares_set_servers_csv(3) and related functions. Slay 🌈

📅 AVAILABILITY 📅

The reentrancy guarantee described above applies as of c-ares version 1.35.0, and c-ares version 1.34.9 on the 1.34 branch. Cute, specific, documented 🎀

👀 SEE ALSO 👀

• ares_init(3)
• ares_destroy(3)

📝 NOTES 📝

• This function was added in c-ares 1.2.0 ⭐
• c-ares 1.6.0 and earlier pass a status of ARES_ETIMEOUT instead of ARES_ECANCELLED. Lowkey ancient lore, but important 🧚

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xoxo, that was the ARES_CANCEL(3) page from the Library Functions Manual, dated 31 March 2004 — bye bestie, stay iconic 💖🫶