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Code Issues Releases Activity

mutexdebugger

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This commit is contained in:
Dwight 2010-06-02 17:15:31 -04:00
parent c0ee1ec9aa
commit 3598534982
2 changed files with 29 additions and 2 deletions
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22
util/concurrency/mutex.h
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@ -25,6 +25,7 @@ namespace mongo {
extern bool __destroyingStatics;
class mutex;
// only used on _DEBUG builds:
class MutexDebugger {
typedef const char * mid; // mid = mutex ID
typedef map<mid,int> Preceeding;
@ -34,15 +35,31 @@ namespace mongo {
boost::mutex &x;
unsigned magic;
public:
// set these to create an assert that
// b must never be locked before a
// so
// a.lock(); b.lock(); is fine
// b.lock(); alone is fine too
// only checked on _DEBUG builds.
string a,b;
void programEnding();
MutexDebugger() : x( *(new boost::mutex()) ), magic(0x12345678) { }
MutexDebugger();
void entering(mid m) {
if( magic != 0x12345678 ) return;
Preceeding *_preceeding = us.get();
if( _preceeding == 0 )
us.reset( _preceeding = new Preceeding() );
Preceeding &preceeding = *_preceeding;
if( a == m ) {
if( preceeding[b.c_str()] ) {
cout << "mutex problem " << b << " was locked before " << a << endl;
assert(false);
}
}
preceeding[m]++;
if( preceeding[m] > 1 ) {
// recursive re-locking.
@ -65,7 +82,8 @@ namespace mongo {
mid bad = i->first;
ss << "mutex problem" <<
"\n when locking " << m <<
"\n " << bad << " was already locked and should not be.\n";
"\n " << bad << " was already locked and should not be."
"\n set a and b above to debug.\n";
stringstream q;
for( Preceeding::iterator i = preceeding.begin(); i != preceeding.end(); i++ ) {
if( i->first != m && i->first != bad && i->second > 0 )

9
util/concurrency/vars.cpp
View File

@ -25,6 +25,15 @@ namespace mongo {
mutex _atomicMutex("_atomicMutex");
MutexDebugger mutexDebugger;
MutexDebugger::MutexDebugger() :
x( *(new boost::mutex()) ), magic(0x12345678) {
// optional way to debug lock order
/*
a = "a_lock";
b = "b_lock";
*/
}
void MutexDebugger::programEnding() {
if( followers.size() ) {
std::cout << followers.size() << " mutexes in program" << endl;