Shutting down the HTTP server currently breaks off all current requests.
This can create a race condition with RPC `stop` command, where the calling
process never receives confirmation.
This change removes the listening sockets on shutdown so that no new
requests can come in, but no longer breaks off requests in progress.
Meant to fix#6717.
The two timeouts for the server and client, are essentially different:
- In the case of the server it should be a lower value to avoid clients
clogging up connection slots
- In the case of the client it should be a high value to accomedate slow
responses from the server, for example for slow queries or when the
lock is contended
Split the options into `-rpcservertimeout` and `-rpcclienttimeout` with
respective defaults of 30 and 900.
Split StartHTTPServer into InitHTTPServer and StartHTTPServer to give
clients a window to register their handlers without race conditions.
Thanks @ajweiss for figuring this out.
Implement RPCTimerHandler for Qt RPC console, so that `walletpassphrase`
works with GUI and `-server=0`.
Also simplify HTTPEvent-related code by using boost::function directly.
- *Replace usage of boost::asio with [libevent2](http://libevent.org/)*.
boost::asio is not part of C++11, so unlike other boost there is no
forwards-compatibility reason to stick with it. Together with #4738 (convert
json_spirit to UniValue), this rids Bitcoin Core of the worst offenders with
regard to compile-time slowness.
- *Replace spit-and-duct-tape http server with evhttp*. Front-end http handling
is handled by libevent, a work queue (with configurable depth and parallelism)
is used to handle application requests.
- *Wrap HTTP request in C++ class*; this makes the application code mostly
HTTP-server-neutral
- *Refactor RPC to move all http-specific code to a separate file*.
Theoreticaly this can allow building without HTTP server but with another RPC
backend, e.g. Qt's debug console (currently not implemented) or future RPC
mechanisms people may want to use.
- *HTTP dispatch mechanism*; services (e.g., RPC, REST) register which URL
paths they want to handle.
By using a proven, high-performance asynchronous networking library (also used
by Tor) and HTTP server, problems such as #5674, #5655, #344 should be avoided.
What works? bitcoind, bitcoin-cli, bitcoin-qt. Unit tests and RPC/REST tests
pass. The aim for now is everything but SSL support.
Configuration options:
- `-rpcthreads`: repurposed as "number of work handler threads". Still
defaults to 4.
- `-rpcworkqueue`: maximum depth of work queue. When this is reached, new
requests will return a 500 Internal Error.
- `-rpctimeout`: inactivity time, in seconds, after which to disconnect a
client.
- `-debug=http`: low-level http activity logging
