fix: break CurlHandle reference cycle leaking connections

[loks0n]

Problem

Curl::send() registers the header and write callbacks as non-static closures. Closures declared in an instance method bind $this, and curl_setopt stores them on the CurlHandle — which the adapter itself holds:

adapter → CurlHandle → closure → adapter

This reference cycle keeps the handle alive after the last external reference to the Client is dropped, so __destruct (and its curl_close) only runs when PHP's cycle collector fires — by default after 10,000 cycle roots accumulate. Until then, every request from a fresh Client leaks an open keep-alive connection: 2 fds and ~1MB of native TLS buffers per request, invisible to memory_get_usage().

In long-running processes (Swoole workers) doing per-request new Client(), this is catastrophic: we traced an hourly OOMKill of Appwrite Cloud's billing aggregation worker to exactly this — a single worker child held 400+ ESTABLISHED TLS connections and >100MB of native memory mid-job.

Measurements (150 sequential requests, one process)

	fds	private-dirty RSS
before	309 (grows +2/req)	183MB (grows ~1MB/req)
after (static closures)	9 (flat)	31MB (flat)

Fix

Mark both callbacks static — neither uses $this, so this is behavior-preserving and simply prevents the binding that forms the cycle.

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

Prevents retained cURL connections by making the header and response-body callbacks static, removing their implicit reference to the adapter instance.

Confidence Score: 5/5

The PR appears safe to merge with no actionable defects identified.

The modified callbacks use only parameters and explicitly captured local variables, and the repository's supported PHP versions accept static closures.

Important Files Changed

Filename	Overview
src/Adapter/Curl.php	Both cURL callbacks are now static; neither accesses instance state, so callback behavior remains unchanged while the CurlHandle reference cycle is removed.

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