Fix socket reuse

[JC-comp]

Summary

onedrive/src/curlEngine.d

Lines 80 to 86 in 5dedd26

	// https://curl.se/libcurl/c/CURLOPT_FORBID_REUSE.html
	// CURLOPT_FORBID_REUSE - make connection get closed at once after use
	// Ensure that we ARE NOT reusing TCP sockets connections - setting to 0 ensures that we ARE reusing connections (we did this in v2.4.xx) to ensure connections remained open and usable
	// Setting this to 1 ensures that when we close the curl instance, any open sockets are closed - which we need to do when running
	// multiple threads and API instances at the same time otherwise we run out of local files | sockets pretty quickly
	// The libcurl default is 1 - ensure we are configuring not to reuse connections and leave unused sockets open
	http.handle.set(CurlOption.forbid_reuse,1);

The use of CURLOPT_FORBID_REUSE above to handle socket exhaustion is a misuse, it does not help solve the problem at all, and will affect the performance of reusable sockets. Please check how tcp socket termination works to see why it doesn't help.

Note: Setting this option will force the socket to be closed on every request. Even if you reuse the curlEngine instance, the socket will still be closed.

Changes

• Remove misuse of CURLOPT_FORBID_REUSE
• Use connection header to ask server close the connection

[abraunegg]

@JC-comp
This appears to be 100% cleaner and a much better way to handle this situation - many thanks for this work.

[abraunegg]

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