private Task <SnippetResult> DoStuffAndReturnWhenIdFinished(Guid snippetId)
{
// Use a TCS for a Task without a "thread"
// http://blogs.msdn.com/b/pfxteam/archive/2009/06/02/9685804.aspx
var tcs = new TaskCompletionSource <SnippetResult>();
try {
// Post in queue, and return immediately
// The pool/deque will "call us back" (set the status) when finished
var snippetData = repository.Get(snippetId);
var snippetInfo = new SnippetInfo()
{
assemblyFile = snippetData.AssemblyBytes,
mainTypeName = SnippetData.SnippetTypeName,
methodName = SnippetData.SnippetMethodName,
submissionId = Guid.NewGuid().ToString()
};
domainPool.SubmitSnippet(snippetInfo, tcs);
}
catch (Exception ex) {
tcs.TrySetException(ex);
}
// Return immediately, with the task we can await on
return(tcs.Task);
}
internal void SubmitSnippet(SnippetInfo snippetInfo, TaskCompletionSource <SnippetResult> completion)
{
// check if we need to re-introduce some domains in the pool
if (Interlocked.Read(ref numberOfThreadsInPool) < NumberOfDomainsInPool)
{
// A sort of "double-check optimization": we enter here only if there is a shortage of threads/domains, but
// we actually create one only if there is a slot
int emptySlotIdx = -1;
lock (poolLock) {
// find the empty slot
for (int i = 0; i < NumberOfDomainsInPool; ++i)
{
if (poolDomains[i] == null)
{
poolDomains[i] = new PooledDomainData();
emptySlotIdx = i;
}
}
}
if (emptySlotIdx >= 0)
{
var thread = CreateDomainThread(emptySlotIdx);
thread.Start();
}
}
// Store the continuation _before_ adding the snippet info the the processing queue
if (!String.IsNullOrEmpty(snippetInfo.submissionId) && completion != null)
{
submissionMap[snippetInfo.submissionId] = completion;
}
snippetsQueue.Add(snippetInfo);
}
internal void SubmitSnippet(SnippetInfo snippetInfo)
{
SubmitSnippet(snippetInfo, null);
}
private Thread CreateDomainThread(int threadIndex)
{
System.Diagnostics.Debug.WriteLine("CreateDomainThread: " + threadIndex);
var myPoolDomain = poolDomains[threadIndex];
var thread = new Thread(() => {
Interlocked.Increment(ref numberOfThreadsInPool);
// Here we enforce the "one domain, one thread" relationship
try {
var appDomain = AppDomainHelpers.CreateSandbox("Host Sandbox");
var manager = (SimpleHostAppDomainManager)appDomain.DomainManager;
lock (poolLock) {
myPoolDomain.domainId = appDomain.Id;
}
while (!snippetsQueue.IsCompleted)
{
defaultDomainManager.ResetContextFor(myPoolDomain);
// And here is were we "rent" one AppDomain and use it to run a snippet
SnippetInfo snippetToRun = null;
try {
snippetToRun = snippetsQueue.Take();
}
catch (InvalidOperationException) {
// Someone called "complete". No more snippets in this process.
// We want to exit the pool.
return;
}
if (snippetToRun != null)
{
System.Diagnostics.Debug.WriteLine("Starting snippet '" + snippetToRun.methodName + "' in domain " + myPoolDomain.domainId);
SnippetResult result = new SnippetResult();
bool recycleDomain = false;
try {
Interlocked.Increment(ref myPoolDomain.numberOfUsages);
// Record when we started
long startTimestamp = StopwatchExtensions.GetTimestampMillis();
System.Diagnostics.Debug.WriteLine("Starting execution at " + startTimestamp);
Thread.VolatileWrite(ref myPoolDomain.timeOfSubmission, startTimestamp);
// Thread transitions into the AppDomain
// This function DOES NOT throw
result = manager.InternalRun(appDomain, snippetToRun.assemblyFile, snippetToRun.mainTypeName, snippetToRun.methodName, true);
// ...back to the main AppDomain
Debug.Assert(AppDomain.CurrentDomain.IsDefaultAppDomain());
long currentTime = StopwatchExtensions.GetTimestampMillis();
result.executionTime = currentTime - Thread.VolatileRead(ref myPoolDomain.timeOfSubmission);
// Flag it as "not executing"
Thread.VolatileWrite(ref myPoolDomain.timeOfSubmission, 0);
}
catch (ThreadAbortException ex) {
// Someone called abort on us.
result.exception = ex.Message;
// It may be possible to use this domain again, otherwise we will recycle
if (Object.Equals(ex.ExceptionState, timeoutAbortToken))
{
// The abort was issued by us because we timed out
System.Diagnostics.Debug.WriteLine("Thread Abort due to timeout");
result.status = SnippetStatus.Timeout;
}
else if (Object.Equals(ex.ExceptionState, threadsExaustedAbortToken))
{
System.Diagnostics.Debug.WriteLine("Thread Abort due to thread exaustion");
result.status = SnippetStatus.ResourceError;
}
else
{
// If it wasn't us, give us time to record the result; we will recycle (unload) the domain
System.Diagnostics.Debug.WriteLine("Thread Abort due to external factors");
result.status = SnippetStatus.CriticalError;
recycleDomain = true;
}
// Give us time to record the result; if needed, we will recycle (unload) the domain later
Thread.ResetAbort();
}
catch (Exception ex) {
result.exception = ex.Message;
// Check if someone is misbehaving, throwing something else to "mask" the TAE
if (Thread.CurrentThread.ThreadState == System.Threading.ThreadState.AbortRequested)
{
result.status = SnippetStatus.CriticalError;
recycleDomain = true;
// Give us time to record the result; we will recycle (unload) the domain
Thread.ResetAbort();
}
else
{
result.status = SnippetStatus.ExecutionError;
}
}
// "Although C# only allows you to throw objects of type Exception and types deriving from it,
// other languages don’t have any such restriction."
// http://weblogs.asp.net/kennykerr/introduction-to-msil-part-5-exception-handling
// It turns out this is no longer necessary
// http://blogs.msdn.com/b/jmanning/archive/2005/09/16/469091.aspx
// catch { }
// No need to catch StackOverflowException; the Host will escalate to a (rude) domain unload
// for us
// TODO: check that AppDomain.DomainUnload is called anyway!
// Before looping, check if we are OK; we reuse the domain only if we are not leaking
int threadsInDomain = defaultDomainManager.GetThreadCount(appDomain.Id);
int memoryUsage = defaultDomainManager.GetMemoryUsage(appDomain.Id);
System.Diagnostics.Debug.WriteLine("============= AppDomain {0} =============", appDomain.Id);
System.Diagnostics.Debug.WriteLine("Finished in: {0}", result.executionTime);
System.Diagnostics.Debug.WriteLine("Status: {0}", result.status);
if (result.exception != null)
{
System.Diagnostics.Debug.WriteLine("Exception: " + result.exception);
}
System.Diagnostics.Debug.WriteLine("Threads: {0}", threadsInDomain);
System.Diagnostics.Debug.WriteLine("Memory: {0}", memoryUsage);
System.Diagnostics.Debug.WriteLine("========================================");
if (threadsInDomain > 1)
{
// The snippet is leaking threads
// Flag snippet as "leaking"
result.status = SnippetStatus.CriticalError;
System.Diagnostics.Debug.WriteLine("Leaking snippet");
recycleDomain = true;
}
else if (MaxReuse > 0 && myPoolDomain.numberOfUsages >= MaxReuse)
{
System.Diagnostics.Debug.WriteLine("Domain too old");
// Same if the domain is too old
recycleDomain = true;
}
// Return the result to the caller
if (!String.IsNullOrEmpty(snippetToRun.submissionId))
{
var completion = submissionMap[snippetToRun.submissionId];
// TCS is thread-safe (can be called cross-thread)
completion.TrySetResult(result);
}
if (recycleDomain)
{
System.Diagnostics.Debug.WriteLine("Recycling domain...");
RecycleDomain(threadIndex);
}
else
{
// Otherwise, ensure that what was allocated by the snippet is freed
GC.Collect();
System.Diagnostics.Debug.WriteLine("MonitoringSurvivedMemorySize {0}", appDomain.MonitoringSurvivedMemorySize);
System.Diagnostics.Debug.WriteLine("MonitoringTotalAllocatedMemorySize {0}", appDomain.MonitoringTotalAllocatedMemorySize);
System.Diagnostics.Debug.WriteLine("MonitoringTotalProcessorTime {0}", appDomain.MonitoringTotalProcessorTime);
}
}
}
}
catch (Exception ex) {
System.Diagnostics.Debug.WriteLine("Exception caught:\n" + ex.ToString());
RecycleDomain(threadIndex);
}
});
thread.Name = "DomainPool thread " + threadIndex;
myPoolDomain.mainThread = thread;
thread.Priority = ThreadPriority.BelowNormal;
return(thread);
}