Initial implementation (hardcoded base package, unordered causes)

Author: Mikel Pascual

src/main/java/com/akaita/java/rxjava2debug/RxJava2Debug.java

@@ -0,0 +1,115 @@
+/*
+ * Copyright 2017 akaita
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.akaita.java.rxjava2debug;
+
+import hu.akarnokd.rxjava2.debug.RxJavaAssemblyException;
+import hu.akarnokd.rxjava2.debug.RxJavaAssemblyTracking;
+import io.reactivex.annotations.NonNull;
+import io.reactivex.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class RxJava2Debug {
+    //Example: "at com.akaita.fgas.MainActivity.onCreate(MainActivity.java:210)"
+    private static final Pattern STACK_TRACE_ELEMENT_PATTERN = Pattern.compile("^at (.*)\\.(.*)\\((.*):([0-9]+)\\)$");
+    private static final String NEW_LINE_REGEX = "\\n\\r|\\r\\n|\\n|\\r";
+
+    private static String BASE_APP_PACKAGE_NAME = "com.akaita.fgas";
+
+    /**
+     * Enable a system to collect information about RxJava's execution to provide a more meaningful StackTrace in case of crash<br/>
+     * <b>Beware:</b> Any crash-reporting handler should be set up <i>before</i> calling this method
+     */
+    public static void enableRxJavaAssemblyTracking() {
+        RxJavaAssemblyTracking.enable();
+        setRxJavaAssemblyHandler();
+    }
+
+    /**
+     * Set handler to intercept an exception, improve the StackTrace of RxJava-related ones and rethrow let the exception go through
+     */
+    private static void setRxJavaAssemblyHandler() {
+        final Thread.UncaughtExceptionHandler previousDefaultHandler = Thread.getDefaultUncaughtExceptionHandler();
+        Thread.setDefaultUncaughtExceptionHandler(new Thread.UncaughtExceptionHandler() {
+            @Override
+            public void uncaughtException(Thread t, Throwable e) {
+                Throwable toThrow = e;
+
+                RxJavaAssemblyException assembledException = RxJavaAssemblyException.find(e);
+                if (assembledException != null) {
+                    StackTraceElement[] clearStack = parseStackTrace(assembledException);
+                    Throwable clearException = new Throwable(e);
+                    clearException.setStackTrace(clearStack);
+                    toThrow = clearException;
+                }
+
+                previousDefaultHandler.uncaughtException(t, toThrow);
+            }
+        });
+    }
+
+    /**
+     * Extract StackTrace and filter to show an app-specific entry at its top
+     *
+     * @param exception RxJavaAssemblyException to be parsed
+     * @return StackTrace, filtered so a app-specific line is at the top of it
+     */
+    private @NonNull
+    static StackTraceElement[] parseStackTrace(@NonNull RxJavaAssemblyException exception) {
+        String[] lines = exception.stacktrace()
+                .split(NEW_LINE_REGEX);
+
+        List<StackTraceElement> stackTrace = new ArrayList<StackTraceElement>();
+        boolean appSpecificFound = false;
+        for (String line : lines) {
+            appSpecificFound = appSpecificFound || line.contains(BASE_APP_PACKAGE_NAME);
+            if (appSpecificFound) {
+                StackTraceElement element = parseStackTraceLine(line);
+                if (element != null) {
+                    stackTrace.add(element);
+                }
+            }
+        }
+
+        return stackTrace.toArray(new StackTraceElement[0]);
+    }
+
+    /**
+     * Parse string containing a <i>single line</i> of a StackTrace
+     *
+     * @param stackTraceLine string containing single line of a StackTrace
+     * @return parsed StackTraceElement
+     */
+    private @Nullable
+    static StackTraceElement parseStackTraceLine(@NonNull String stackTraceLine) {
+        StackTraceElement retVal = null;
+
+        Matcher matcher = STACK_TRACE_ELEMENT_PATTERN.matcher(stackTraceLine);
+        if (matcher.matches()) {
+            String clazz = matcher.group(1);
+            String method = matcher.group(2);
+            String filename = matcher.group(3);
+            int line = Integer.valueOf(matcher.group(4));
+            retVal = new StackTraceElement(clazz, method, filename, line);
+        }
+        return retVal;
+    }
+
+}