Add getdeprecationinfo RPC method to return deprecation block height
Closes#2828
Returns:
```
{
"version": xxxxx, (numeric) the server version
"subversion": "/MagicBean:x.y.z[-v]/", (string) the server subversion string
"deprecationheight": xxxxx, (numeric) the deprecation block height
}
```
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.
Zcash: QT changes ommitted
- *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
- implement find_value() function for UniValue
- replace all Array/Value/Object types with UniValues, remove JSON Spirit to UniValue wrapper
- remove JSON Spirit sources
"Block difficulty" is the difficulty listed in a block's header, which in the
testnet can sometimes be min-difficulty (if time-since-last-block is too large).
"Network difficulty" is the difficulty that the network was trying to satisfy
at a particular block height. In mainnet this is always equal to the difficulty
of the solved block for that height, but in testnet the network difficulty is
derived from the last non-min-difficulty block difficulty.
This commit fixes the RPC APIs that are intended to show network difficulty, so
that on testnet they don't sometimes drop to 1.0, confusing users.
Closes#1181
