libwebsockets/minimal-examples/http-client/minimal-http-client-attach/README.md

# lws minimal http client attach

This demonstrates how other threads can reach out to an existing lws_context
and join its event loop cleanly and safely.

## build

```
 $ cmake . && make
```

Pthreads is required on your system.

## usage

```
 $ ./lws-minimal-http-client-attach
[2019/12/31 18:30:49:3495] U: main: main thread tid 0x503e1c0
[2019/12/31 18:30:50:3584] U: LWS minimal http client attach
[2019/12/31 18:30:50:4002] U: lws_create: tid 0x5c41700
[2019/12/31 18:30:50:5727] E: callback_ntpc: set up system ops for set_clock
[2019/12/31 18:30:50:2110] N: callback_ntpc: Unix time: 1577817053
[2019/12/31 18:30:50:2136] U: attach_callback: called from tid 0x5c41700
[2019/12/31 18:30:51:8733] U: Connected to 46.105.127.147, http response: 200
[2019/12/31 18:30:51:8818] U: RECEIVE_CLIENT_HTTP_READ: read 4087
[2019/12/31 18:30:51:8823] U: RECEIVE_CLIENT_HTTP_READ: read 4096
[2019/12/31 18:30:51:8846] U: RECEIVE_CLIENT_HTTP_READ: read 4087
[2019/12/31 18:30:51:8847] U: RECEIVE_CLIENT_HTTP_READ: read 4096
[2019/12/31 18:30:51:8855] U: RECEIVE_CLIENT_HTTP_READ: read 4087
[2019/12/31 18:30:51:8856] U: RECEIVE_CLIENT_HTTP_READ: read 4096
[2019/12/31 18:30:51:8860] U: RECEIVE_CLIENT_HTTP_READ: read 1971
[2019/12/31 18:30:51:8873] U: LWS_CALLBACK_COMPLETED_CLIENT_HTTP
[2019/12/31 18:30:51:9629] U: main: finished
```
lws_system: helpers for attaching to existing event loop from other threads In the case code is composed into a single process, but it isn't monolithic in the sense it's made up of modular "applications" that are written separate projects, provide a way for the "applications" to request a callback from the lws event loop thread context safely. From the callback the applications can set up their operations on the lws event loop and drop their own thread. Since it requires system-specific locking to be threadsafe, provide a non-threadsafe helper and then indirect the actual usage through a user-defined lws_system ops function pointer that wraps the unsafe api with the system locking to make it safe. 2019-12-31 15:24:58 +00:00			`# lws minimal http client attach`

			`This demonstrates how other threads can reach out to an existing lws_context`
			`and join its event loop cleanly and safely.`

			`## build`

			```
			`$ cmake . && make`
			```

			`Pthreads is required on your system.`

			`## usage`

			```
			`$ ./lws-minimal-http-client-attach`
			`[2019/12/31 18:30:49:3495] U: main: main thread tid 0x503e1c0`
			`[2019/12/31 18:30:50:3584] U: LWS minimal http client attach`
			`[2019/12/31 18:30:50:4002] U: lws_create: tid 0x5c41700`
			`[2019/12/31 18:30:50:5727] E: callback_ntpc: set up system ops for set_clock`
			`[2019/12/31 18:30:50:2110] N: callback_ntpc: Unix time: 1577817053`
			`[2019/12/31 18:30:50:2136] U: attach_callback: called from tid 0x5c41700`
			`[2019/12/31 18:30:51:8733] U: Connected to 46.105.127.147, http response: 200`
			`[2019/12/31 18:30:51:8818] U: RECEIVE_CLIENT_HTTP_READ: read 4087`
			`[2019/12/31 18:30:51:8823] U: RECEIVE_CLIENT_HTTP_READ: read 4096`
			`[2019/12/31 18:30:51:8846] U: RECEIVE_CLIENT_HTTP_READ: read 4087`
			`[2019/12/31 18:30:51:8847] U: RECEIVE_CLIENT_HTTP_READ: read 4096`
			`[2019/12/31 18:30:51:8855] U: RECEIVE_CLIENT_HTTP_READ: read 4087`
			`[2019/12/31 18:30:51:8856] U: RECEIVE_CLIENT_HTTP_READ: read 4096`
			`[2019/12/31 18:30:51:8860] U: RECEIVE_CLIENT_HTTP_READ: read 1971`
			`[2019/12/31 18:30:51:8873] U: LWS_CALLBACK_COMPLETED_CLIENT_HTTP`
			`[2019/12/31 18:30:51:9629] U: main: finished`
			```