parity-clib: async C bindings to RPC requests + subscribe/unsubscribe to websocket events (#9920)

* feat(parity-clib asynchronous rpc queries)

* feat(seperate bindings for ws and rpc)

* Subscribing to websockets for the full-client works

* feat(c binding unsubscribe_from_websocket)

* fix(tests): tweak CMake build config

* Enforce C+11

* refactor(parity-cpp-example) : `cpp:ify`

* fix(typedefs) : revert typedefs parity-clib

* docs(nits)

* fix(simplify websocket_unsubscribe)

* refactor(cpp example) : more subscriptions

* fix(callback type) : address grumbles on callback

* Use it the example to avoid using global variables

* docs(nits) - don't mention `arc`

* fix(jni bindings): fix compile errors

* feat(java example and updated java bindings)

* fix(java example) : run both full and light client

* fix(Java shutdown) : unsubscribe to sessions

Forgot to pass the JNIEnv environment since it is an instance method

* feat(return valid JString)

* Remove Java dependency by constructing a valid Java String in the callback

* fix(logger) : remove `rpc` trace log

* fix(format)

* fix(parity-clib): remove needless callback `type`

* fix(parity-clib-examples) : update examples

* `cpp` example pass in a struct instead to determines `callback kind`
* `java` add a instance variable the class `Callback` to determine `callback kind`

* fix(review comments): docs and format

* Update parity-clib/src/java.rs

Co-Authored-By: niklasad1 <niklasadolfsson1@gmail.com>

* fix(bad merge + spelling)

* fix(move examples to parity-clib/examples)

parity-clib/examples/java/Main.java

@@ -0,0 +1,109 @@
+// Copyright 2018 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+import java.util.Vector;
+import java.util.concurrent.atomic.AtomicInteger;
+import io.parity.ethereum.Parity;
+
+class Main {
+	public static final int ONE_MINUTE_AS_MILLIS = 60 * 1000;
+
+	public static final String[] rpc_queries = {
+		"{\"method\":\"parity_versionInfo\",\"params\":[],\"id\":1,\"jsonrpc\":\"2.0\"}",
+		"{\"method\":\"eth_getTransactionReceipt\",\"params\":[\"0x444172bef57ad978655171a8af2cfd89baa02a97fcb773067aef7794d6913fff\"],\"id\":1,\"jsonrpc\":\"2.0\"}",
+		"{\"method\":\"eth_estimateGas\",\"params\":[{\"from\":\"0x0066Dc48bb833d2B59f730F33952B3c29fE926F5\"}],\"id\":1,\"jsonrpc\":\"2.0\"}",
+		"{\"method\":\"eth_getBalance\",\"params\":[\"0x0066Dc48bb833d2B59f730F33952B3c29fE926F5\"],\"id\":1,\"jsonrpc\":\"2.0\"}"
+	};
+
+	public static final String[] ws_queries = {
+		"{\"method\":\"parity_subscribe\",\"params\":[\"eth_getBalance\",[\"0xcd2a3d9f938e13cd947ec05abc7fe734df8dd826\",\"latest\"]],\"id\":1,\"jsonrpc\":\"2.0\"}",
+		"{\"method\":\"parity_subscribe\",\"params\":[\"parity_netPeers\"],\"id\":1,\"jsonrpc\":\"2.0\"}",
+		"{\"method\":\"eth_subscribe\",\"params\":[\"newHeads\"],\"id\":1,\"jsonrpc\":\"2.0\"}"
+	};
+
+	public static void runParity(String[] config) {
+		Parity parity = new Parity(config);
+
+		Callback rpcCallback = new Callback(1);
+		Callback webSocketCallback = new Callback(2);
+
+		for (String query : rpc_queries) {
+			parity.rpcQuery(query, ONE_MINUTE_AS_MILLIS, rpcCallback);
+		}
+
+		while (rpcCallback.getNumCallbacks() != 4);
+
+		Vector<Long> sessions = new Vector<Long>();
+
+		for (String ws : ws_queries) {
+			long session = parity.subscribeWebSocket(ws, webSocketCallback);
+			sessions.add(session);
+		}
+
+		try {
+			Thread.sleep(ONE_MINUTE_AS_MILLIS);
+		} catch (Exception e) {
+			System.out.println(e);
+		}
+
+		for (long session : sessions) {
+			parity.unsubscribeWebSocket(session);
+		}
+
+		// Force GC to destroy parity
+		parity = null;
+		System.gc();
+	}
+
+	public static void main(String[] args) {
+		String[] full = {"--no-ipc" , "--jsonrpc-apis=all", "--chain", "kovan"};
+		String[] light = {"--no-ipc", "--light", "--jsonrpc-apis=all", "--chain", "kovan"};
+
+		runParity(full);
+
+		try {
+			Thread.sleep(ONE_MINUTE_AS_MILLIS);
+		} catch (Exception e) {
+			System.out.println(e);
+		}
+
+		runParity(light);
+	}
+}
+
+class Callback {
+	private AtomicInteger counter;
+	private final int callbackType;
+
+	public Callback(int type) {
+		counter = new AtomicInteger();
+		callbackType = type;
+	}
+
+	public void callback(Object response) {
+		response = (String) response;
+		if (callbackType == 1) {
+			System.out.println("rpc: " + response);
+		} else if (callbackType == 2) {
+			System.out.println("ws: " + response);
+		}
+		counter.getAndIncrement();
+	}
+
+	public int getNumCallbacks() {
+		return counter.intValue();
+	}
+}

parity-clib/examples/java/README.md

@@ -0,0 +1,9 @@
+parity-clib: Java example
+===================================
+
+An example Java application to demonstrate how to use `jni` bindings to parity-ethereum. Note, that the example is built in debug-mode to reduce the build time. If you want to use it in real project use release-mode instead to facilitate all compiler optimizations. 
+
+## How to compile and run
+
+1. Make sure you have installed [JDK](https://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html)
+2. Run `run.sh`

parity-clib/examples/java/run.sh

@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+
+FLAGS="-Xlint:deprecation"
+PARITY_JAVA="../../Parity.java"
+# parity-clib must be built with feature `jni` in debug-mode to work
+PARITY_LIB=".:../../../target/debug/"
+
+# build
+cd ..
+cargo build --features jni
+cd -
+javac $FLAGS -d $PWD $PARITY_JAVA
+javac $FLAGS *.java
+# Setup the path `libparity.so` and run
+java -Djava.library.path=$PARITY_LIB Main