Implement memory-mapped ExecutionData class.

This allows apps to write coverage to disk during execution and not
require any flushing mechanism in order to collect coverage. The results
will be left in /data/misc/trace/jacoco-*.mm.ec and can be collected
later for coverage analysis. These .mm.ec files conform to the current
exec file format and can be loaded with the command-line tool.

Test: m -j EMMA_INSTRUMENT=true EMMA_INSTRUMENT_FRAMEWORK=true and
generate coverage report from /data/misc/trace
Bug: 147904124

Change-Id: If08492405b86a063ae714c259a2fb954bc5aa946

1 files changed, 75 insertions, 1 deletions

diff --git a/org.jacoco.agent.rt/src/org/jacoco/agent/rt/internal/Offline.java b/org.jacoco.agent.rt/src/org/jacoco/agent/rt/internal/Offline.java
index ee9d40b1..445722af 100644
--- a/org.jacoco.agent.rt/src/org/jacoco/agent/rt/internal/Offline.java
+++ b/org.jacoco.agent.rt/src/org/jacoco/agent/rt/internal/Offline.java
@@ -11,6 +11,8 @@
  *******************************************************************************/
 package org.jacoco.agent.rt.internal;
 
+import java.io.File;
+import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Properties;
@@ -18,6 +20,7 @@ import java.util.Properties;
 import org.jacoco.core.data.ExecutionData;
 import org.jacoco.core.data.IExecutionData;
 import org.jacoco.core.data.ExecutionDataStore;
+import org.jacoco.core.data.MappedExecutionData;
 import org.jacoco.core.runtime.AgentOptions;
 import org.jacoco.core.runtime.RuntimeData;
 
@@ -30,6 +33,7 @@ public final class Offline {
 	// BEGIN android-change
 	// private static final RuntimeData DATA;
 	private static final Map<Long, IExecutionData> DATA = new HashMap<Long, IExecutionData>();
+	private static int PID = -1;
 	// END android-change
 	private static final String CONFIG_RESOURCE = "/jacoco-agent.properties";
 
@@ -64,7 +68,49 @@ public final class Offline {
 		synchronized (DATA) {
 			IExecutionData entry = DATA.get(classid);
 			if (entry == null) {
-				entry = new ExecutionData(classid, classname, probecount);
+				// BEGIN android-change
+				// The list below are not allowed to use the memory-mapped
+				// implementation due either:
+				//   1) They are loaded at VM initialization time.
+				//	a) android.*
+				//	b) dalvik.*
+				//	c) libcore.*
+				//   2) They are used by the memory-mapped execution data
+				//      implementation, which would cause a stack overflow due
+				//      to the circular dependency.
+				//	a) com.android.i18n.*
+				//	b) com.android.icu.*
+				//	c) java.*
+				//	d) org.apache.*
+				//	e) sun.*
+				// These classes can still have coverage collected through the
+				// normal execution data process, but requires a flush to be done
+				// instead of simply being available on disk at all times.
+				if (classname.startsWith("android/")
+					|| classname.startsWith("com/android/i18n/")
+					|| classname.startsWith("com/android/icu/")
+					|| classname.startsWith("dalvik/")
+					|| classname.startsWith("java/")
+					|| classname.startsWith("libcore/")
+					|| classname.startsWith("org/apache/")
+					|| classname.startsWith("sun/")) {
+					entry = new ExecutionData(classid, classname, probecount);
+				} else {
+					try {
+						int pid = getPid();
+						if (PID != pid) {
+							PID = pid;
+							rebuildExecutionData(pid);
+						}
+						entry = new MappedExecutionData(
+							classid, classname, probecount);
+					} catch (IOException e) {
+						// Fall back to non-memory-mapped execution data.
+						entry = new ExecutionData(
+							classid, classname, probecount);
+					}
+				}
+				// END android-change
 				DATA.put(classid, entry);
 			} else {
 				entry.assertCompatibility(classid, classname, probecount);
@@ -72,6 +118,34 @@ public final class Offline {
 			return entry;
 		}
 	}
+
+	private static void rebuildExecutionData(int pid) throws IOException {
+		MappedExecutionData.prepareFile(pid);
+		synchronized (DATA) {
+			for (IExecutionData execData : DATA.values()) {
+				if (execData instanceof MappedExecutionData) {
+					// Create new instances of MappedExecutionData using the
+					// new file, but don't copy the old data. Old data will
+					// remain in its existing file and can be merged during
+					// post-processing.
+					DATA.put(
+						execData.getId(),
+						new MappedExecutionData(
+							execData.getId(),
+							execData.getName(),
+							execData.getProbeCount()));
+				}
+			}
+		}
+	}
+
+	/**
+	 * Helper function to determine the pid of this process.
+	 */
+	private static int getPid() throws IOException {
+		// Read /proc/self and resolve it to obtain its pid.
+		return Integer.parseInt(new File("/proc/self").getCanonicalFile().getName());
+	}
 	// END android-change
 
 	/**