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Code Issues Releases Wiki Activity

Merge remote-tracking branch 'origin/GT-3262_emteere_LockProfiler'

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This commit is contained in:
Ryan Kurtz 2019-11-08 13:39:39 -05:00
commit 62da8dcdc3
1 changed files with 24 additions and 14 deletions
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38
Ghidra/Framework/Project/src/main/java/ghidra/util/Lock.java
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@ -1,6 +1,5 @@
/* ###
* IP: GHIDRA
* REVIEWED: YES
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@ -17,18 +16,18 @@
package ghidra.util;
/**
* Ghidra synchronization lock. This class allows creation of named locks for
* modifying tables in the Ghidra data base. This class also creates an instance
* of a global lock that must first be obtained when synchronizing using multiple
* of the named locks.
* Ghidra synchronization lock. This class allows creation of named locks for
* synchroniing modification of multiple tables in the Ghidra database.
*/
public class Lock {
private Thread owner;
private int cnt = 0;
private int lockAquireCount = 0;
private int waiterCount = 0;
private String name;
/**
* Creates an instance of a lock for synchronization within Ghidra.
*
* @param name the name of this lock
*/
public Lock(String name) {
@ -36,26 +35,32 @@ public class Lock {
}
/**
* Acquire this synchronization lock.
* (i.e. begin synchronizing on this named lock.)
* Acquire this synchronization lock. (i.e. begin synchronizing on this named
* lock.)
*/
public synchronized void acquire() {
Thread currThread = Thread.currentThread();
while (true) {
if (owner == null) {
cnt = 1;
lockAquireCount = 1;
owner = currThread;
return;
}
else if (owner == currThread) {
cnt++;
lockAquireCount++;
return;
}
try {
waiterCount++;
wait();
}
catch (InterruptedException e) {
// exception from another threads notify(), ignore
// and try to get lock again
}
finally {
waiterCount--;
}
}
}
@ -67,10 +72,15 @@ public class Lock {
public synchronized void release() {
Thread currThread = Thread.currentThread();
if (cnt > 0 && (owner == currThread)) {
if (--cnt == 0) {
if (lockAquireCount > 0 && (owner == currThread)) {
if (--lockAquireCount == 0) {
owner = null;
notify();
// This is purely to help sample profiling. If notify() is called the
// sampler can attribute time to the methods calling this erroneously. For some reason
// the visualvm sampler gets a sample more often when notify() is called.
if (waiterCount != 0) {
notify();
}
}
}
else {
@ -80,10 +90,10 @@ public class Lock {
/**
* Gets the thread that currently owns the lock.
*
* @return the thread that owns the lock or null.
*/
public Thread getOwner() {
return owner;
}
}