Allow any number of build threads

src/BuildQueue.cpp

@@ -735,15 +735,10 @@ namespace t2
     queue->m_ExpensiveWaitCount = 0;
     queue->m_ExpensiveWaitList  = HeapAllocateArray<NodeState*>(heap, capacity);
 
-    CHECK(queue->m_Queue);
-
-    if (queue->m_Config.m_ThreadCount > kMaxBuildThreads)
-    {
-      Log(kWarning, "too many build threads (%d) - clamping to %d",
-          queue->m_Config.m_ThreadCount, kMaxBuildThreads);
+    queue->m_Threads = HeapAllocateArrayZeroed<ThreadId>(config->m_Heap, config->m_ThreadCount);
+    queue->m_ThreadState = HeapAllocateArrayZeroed<ThreadState>(config->m_Heap, config->m_ThreadCount);
 
-      queue->m_Config.m_ThreadCount = kMaxBuildThreads;
-    }
+    CHECK(queue->m_Queue);
 
     Log(kDebug, "build queue initialized; ring buffer capacity = %u", queue->m_QueueCapacity);
 
@@ -797,6 +792,9 @@ namespace t2
     CondDestroy(&queue->m_WorkAvailable);
     MutexDestroy(&queue->m_Lock);
 
+    HeapFree(config->m_Heap, queue->m_ThreadState);
+    HeapFree(config->m_Heap, queue->m_Threads);
+
     // Unblock all signals on the main thread.
     SignalHandlerSetCondition(nullptr);
     SignalBlockThread(false);

src/BuildQueue.hpp

@@ -17,11 +17,6 @@ namespace t2
   struct StatCache;
   struct DigestCache;
 
-  enum
-  {
-    kMaxBuildThreads = 64
-  };
-
   struct BuildQueueConfig
   {
     enum
@@ -73,8 +68,8 @@ namespace t2
     int32_t            m_PendingNodeCount;
     int32_t            m_FailedNodeCount;
     int32_t            m_CurrentPassIndex;
-    ThreadId           m_Threads[kMaxBuildThreads];
-    ThreadState        m_ThreadState[kMaxBuildThreads];
+    ThreadId          *m_Threads;
+    ThreadState       *m_ThreadState;
     int32_t            m_ExpensiveRunning;
     int32_t            m_ExpensiveWaitCount;
     NodeState        **m_ExpensiveWaitList;