Add Thread_Group implementation from Jai compiler.

lib/Base/Thread_Group.cpp

@@ -0,0 +1,319 @@
+// Thread_Group Internal Procedures
+void init(Work_List* list) {
+  Assert(list != nullptr);
+  
+  semaphore_init(&list->semaphore);
+  mutex_init(&list->mutex);
+}
+
+void destroy(Work_List* list) {
+  Assert(list != nullptr);
+  
+  semaphore_destroy(&list->semaphore);
+  mutex_destroy(&list->mutex);
+}
+
+void add_work(Work_List* list, Work_Entry* entry) {
+  lock(&list->mutex);
+  
+  if (list->last) { // This list has nodes in it. Put this entry onto the end so we're FIFO
+    list->last->next = entry;
+    list->last = entry;
+  } else { // The list is empty, the list will have 1 entry:
+    list->first = entry;
+    list->last  = entry;
+  }
+  
+  list->count += 1;
+  
+  unlock(&list->mutex);
+  
+  signal(&list->semaphore);
+}
+
+Work_Entry* get_work(Work_List* list) {
+  lock(&list->mutex);
+  
+  // Grab first node; may be null if work has been stolen
+  Work_Entry* result = list->first;
+  
+  if (result) {
+    // Update the head of the list to be the next item
+    list->first = result->next;
+    
+    // If the new 'first' pointer is null, the list has become empty, so set 'last' to null also
+    if (list->first == nullptr) {
+      list->last = nullptr;
+    }
+  }
+  
+  unlock(&list->mutex);
+  
+  return result;
+}
+
+s64 thread_group_run (Thread* thread) {
+  // This is the main loop that a particular thread runs.
+  // It waits on its semaphore, looking for new work on its 'available' list.
+  // When it finds work, it calls the thread group procedure with the work,
+  // then puts the work into its 'completed' list.
+  
+  Worker_Info* info = thread->worker_info;
+  Thread_Group* group = info->group;
+  
+  Work_Entry* entry = nullptr;
+  
+  while(!group->should_exit) {
+    if (!entry) {
+      wait_for(&info->available.semaphore);
+      if (group->should_exit) break;
+      
+      // Remove work from the list. Might be none if another thread stole.
+      entry = get_work(&info->available);
+    }
+    
+    if (entry) {
+      entry->thread_index = thread->index;
+      entry->next         = nullptr;
+      
+      // #TODO(Log)
+      
+      Thread_Continue_Status should_continue = Thread_Continue_Status::THREAD_CONTINUE;
+      if (group->proc) {
+        should_continue = group->proc(group, thread, entry->work);
+      }
+      
+      // The work is done, add it to the completed list:
+      add_work(&info->completed, entry);
+      
+      if (should_continue == Thread_Continue_Status::THREAD_STOP) {
+        break;
+      }
+    }
+    
+    if (info->work_steal_indices.count) {
+      if (group->should_exit) break;
+      
+      // Check for more work. If there's none, try to steal some before going to sleep.
+      entry = get_work(&info->available);
+      if (entry) {
+        // Decrement the semaphore for the work we dequeued. 
+        wait_for(&info->available.semaphore);
+      } else { // no work left, let's steal some
+        for (s64 i = 0; i < info->work_steal_indices.count; i += 1) {
+          entry = get_work(&group->worker_info[i].available);
+          if (entry) {
+            // #TODO(Log)
+            break; // for
+          }
+        }
+      }
+    } else {
+      entry = nullptr;
+    }
+  }
+  
+  return 0;
+}
+
+
+// Thread_Group API:
+void init (Thread_Group* group, s32 group_thread_count, Thread_Group_Proc group_proc, 
+            bool enable_work_stealing = false) {
+  // Set allocator if not already set:
+  if (!group->allocator.proc) {
+    group->allocator = get_context_allocator();
+  }
+  
+  push_allocator(group->allocator);
+  
+  group->worker_info = ArrayView<Worker_Info>(group_thread_count);
+  
+  group->proc = group_proc;
+  
+  for (s64 i = 0; i < group->worker_info.count; i += 1) {
+    Worker_Info* info = &group->worker_info[i];
+    thread_init(&info->thread, thread_group_run);
+    
+    info->thread.worker_info = info;
+    
+    init(&info->available);
+    init(&info->completed);
+    
+    info->group = group;
+    info->worker_index = (s32)i;
+    
+    if (enable_work_stealing) {
+      // Make an array that contains all worker indices except for ours.
+      // This gets shuffled for work stealing. Why? Because we want to
+      // search through 2 threads for work, but if they are mostly empty,
+      // we might have to scan through the whole array anyway. Maybe this
+      // is not the best way to do it.
+      
+      info->work_steal_indices = ArrayView<s32>(group_thread_count-1, false);
+      s32 cursor = 0;
+      for (s32 j = 0; j < group_thread_count; j += 1) {
+        if (j == i) continue;
+        
+        info->work_steal_indices[cursor] = j;
+        cursor += 1;
+      }
+    }
+  }
+  
+  group->initialized = true;
+}
+
+void start (Thread_Group* group) {
+  Assert(group->worker_info.count > 0);
+  for (s64 i = 0; i < group->worker_info.count; i += 1) {
+    Worker_Info* info = &group->worker_info[i];
+    thread_start(&info->thread);
+  }
+  
+  group->started = true;
+}
+
+bool shutdown (Thread_Group* group, s32 timeout_milliseconds = -1) {
+  Assert(group->initialized);
+  
+  group->should_exit = true;
+  
+  bool all_threads_done = true;
+  
+  if (group->started) {
+    for (s64 i = 0; i < group->worker_info.count; i += 1) {
+      Worker_Info* info = &group->worker_info[i];
+      signal(&info->available.semaphore);
+    }
+    
+    f64 start = 0;
+    if (timeout_milliseconds > 0) {
+      start = GetUnixTimestamp();
+    }
+    s64 remaining_timeout_ms = (s64)timeout_milliseconds;
+    
+    for (s64 i = 0; i < group->worker_info.count; i += 1) {
+      Worker_Info* info = &group->worker_info[i];
+      
+      if (remaining_timeout_ms > 0) {
+        s64 time_elapsed_ms = (s64)((GetUnixTimestamp() - start) * 1000.0);
+        remaining_timeout_ms = (timeout_milliseconds - time_elapsed_ms);
+        
+        if (remaining_timeout_ms < 0)
+            remaining_timeout_ms = 0;
+      }
+      
+      bool is_done = thread_is_done(&info->thread, (s32)remaining_timeout_ms);
+      if (!is_done) 
+          all_threads_done = false;
+    }
+  }
+  
+  if (!all_threads_done) return false;
+  
+  for (s64 i = 0; i < group->worker_info.count; i += 1) {
+    Worker_Info* info = &group->worker_info[i];
+    thread_deinit(&info->thread);
+    destroy(&info->available);
+    destroy(&info->completed);
+    array_free(info->work_steal_indices);
+  }
+  
+  array_free(group->worker_info);
+  
+  return true;
+}
+
+// Should have a shutdown_and_reset option too (see how I did it in prototyping-main)
+
+void add_work (Thread_Group* group, void* work) { // string logging_name
+  Assert(group->worker_info.count > 0);
+  
+  push_allocator(group->allocator);
+  
+  // Make a work entry, a linked list node that lets us queue and unqueue
+  Work_Entry* entry = New<Work_Entry>();
+  entry->work = work;
+  // entry->logging_name = "";
+  entry->issue_time = GetUnixTimestamp();
+  
+  // Choose which thread will run this work.
+  s32 thread_index = group->next_worker_index;
+  group->next_worker_index += 1;
+  
+  if (group->next_worker_index >= group->worker_info.count) {
+    group->next_worker_index = 0;
+  }
+  
+  entry->work_list_index = thread_index;
+  
+  // Add this node to the linked list of available work for that thread:
+  Work_List* list = &group->worker_info[thread_index].available;
+  add_work(list, entry);
+  
+  // #TODO: Log if necessary.
+}
+
+ArrayView<void*> get_completed_work (Thread_Group* group) {
+  Array<void*> results = Array<void*>();
+  results.allocator = get_temp_allocator();
+  
+  push_allocator(group->allocator);
+  
+  // We iterate over every worker thread to see if anything has completed.
+  // Note that if this Thread_Group is idle most of the time, and you call
+  // get_completed_work once per frame, most of the time this loop will
+  // just be waste. Hopefully it's not very much waste compared to everything else
+  // your program is doing, but in the future we may add an early-out:
+  // if all work was completed before, and we never added new work, obviously
+  // we don't need to do anything, as there can't be any new work.
+  for (s64 i = 0; i < group->worker_info.count; i += 1) {
+    Worker_Info* info = &group->worker_info[i];
+    Work_List* list = &info->completed;
+    Work_Entry* completed = nullptr;
+    
+    s32 new_count = 0;
+    
+    { lock(&list->mutex);
+      new_count = list->count;
+      completed = list->first;
+      
+      if (list->first) {
+        list->first = nullptr;
+        list->last  = nullptr;
+        list->count = 0;
+      }
+      
+      unlock(&list->mutex);
+    }
+    
+    if (!completed) continue;
+    
+    // Reserve the output array. Probably doesn't help much. Note that
+    // we are maybe adding small numbers of results over a larger number
+    // of cores. Really if we want to be efficient here, we can build
+    // a larger linked list out of the mini-lists we gather, and accumulate
+    // the counts, then do the reserve all in one batch when we are done
+    // looking at the threads. For simplicity this has not yet been done,
+    // but it may not be much more complicated, actually.
+    // #TODO(Musa) - do this^
+    array_reserve(results, results.count + new_count);
+    s64 old_count = results.count;
+    
+    while (completed) {
+      array_add(results, completed->work);
+      Work_Entry* next = completed->next;
+      
+      // #TODO(Log)
+      
+      internal_free(completed);
+      completed = next;
+    }
+    
+    Assert(results.count == old_count + new_count);
+  }
+  
+  return {};
+}
+

lib/Base/Threads.cpp

@@ -36,21 +36,77 @@
 #endif
 
 struct Thread;
+// really hacky forward declares.
+struct Work_Entry;
+struct Worker_Info;
+struct Work_List;
+struct Thread_Group; 
+void init(Work_List* list);
+void destroy(Work_List* list);
+
 typedef s64 (*Thread_Proc)(Thread* thread); 
+s64 thread_group_run (Thread* thread);
 struct Thread {
   Thread_Context* context;
-  s64 index;
   Thread_Proc proc;
   void* data;
   
+  s64 index;
+  
   OS_Thread os_thread;
+  
+  // Used by Thread_Group
+  Worker_Info* worker_info;
 };
 
 global u32 next_thread_index = 1;
 
-// internal Thread thread_start
 
+// Thread Group API (Copied from Jonathan Blow's implementation - I did not come up with this.)
 
-// thread_create -> os_thread_launch
-// thread_join   -> os_thread_join
-// thread_detach -> os_thread_detach
+struct Work_Entry {
+  Work_Entry* next;
+  void* work;
+  s64 thread_index; // Thread.index for the thread that handled this work
+  // string logging_name;
+  f64 issue_time;
+  s32 work_list_index;
+};
+struct Work_List {
+  Semaphore semaphore;
+  Mutex mutex;
+  Work_Entry* first;
+  Work_Entry* last;
+  s32 count;
+};
+struct Worker_Info {
+  Thread thread;
+  Work_List available;
+  Work_List completed;
+  Thread_Group* group;
+  s32 worker_index;
+  u8 padding0[44];
+  // Work steal indices should be on another cache line:
+  ArrayView<s32> work_steal_indices;
+  u8 padding1[48];
+};
+static_assert(sizeof(Worker_Info) % 64 == 0); // This MUST be padded to cache line!
+enum class Thread_Continue_Status : s32 {
+  THREAD_STOP = 0,
+  THREAD_CONTINUE = 1 
+};
+typedef Thread_Continue_Status (*Thread_Group_Proc)(Thread_Group* group, Thread* thread, void* work);
+struct Thread_Group {
+  void* data;
+  Thread_Group_Proc proc;
+  string name;
+  
+  Allocator allocator; // for allocating work indices
+  ArrayView<Worker_Info> worker_info; // only alloc'd once with allocator??
+  s32 next_worker_index;
+  
+  bool initialized = false;
+  bool started     = false;
+  bool should_exit = false;
+  // bool enable_logging;
+};

lib/OS/Base_Entry_Point.cpp

@@ -13,7 +13,6 @@ internal void Bootstrap_Main_Thread_Context () {
   thread_local_context->thread_name = "Main Thread";
   // thread_local_context->logger     = init_logger();
 
-  // debug_break();
 }
 
 // #include "lib/Base/Arena_Array.h"
@@ -39,6 +38,12 @@ void run_arena_array_tests () {
 internal void Main_Entry_Point (int argc, WCHAR **argv) {
   run_arena_array_tests();
 
+  Worker_Info* info = (Worker_Info*)GPAllocator_New(sizeof(Worker_Info), 64);
+  
+  debug_break();
+  printf("sizeof(Worker_Info): %zd\n", sizeof(Thread));
+  printf("sizeof(Worker_Info): %zd\n", sizeof(Worker_Info));
+  
   // #TODO:
   // [ ] Launch second thread
   // [ ] Setup Mouse and Keyboard Inputs 

lib/OS/OS_Win32.cpp

@@ -67,6 +67,8 @@ internal LONG WINAPI Win32_Exception_Filter (EXCEPTION_POINTERS* exception_ptrs)
   return 0;
 }
 
+internal void Bootstrap_Main_Thread_Context ();
+// internal void Main_Entry_Point (int argc, WCHAR **argv);
 internal void Win32_Entry_Point (int argc, WCHAR **argv) {
   // See: w32_entry_point_caller(); (raddebugger)
   SetUnhandledExceptionFilter(&Win32_Exception_Filter);
@@ -158,8 +160,6 @@ internal void Win32_Entry_Point (int argc, WCHAR **argv) {
     }
   }
   
-  // debug_break();
-  
   { OS_Process_Info* info = &os_state_w32.process_info;
     DWORD length = GetCurrentDirectoryW(0, 0);
     // This can be freed later when we call temp_reset();
@@ -187,8 +187,8 @@ C_LINKAGE DWORD OS_Windows_Thread_Entry_Point (void* parameter) {
   return result;
 }
 
-// OS_Thread stuff
-internal bool thread_init (Thread* thread, Thread_Proc proc, string thread_name) {
+// Individual Thread API
+internal bool thread_init (Thread* thread, Thread_Proc proc, string thread_name="") {
   Assert(thread != nullptr && proc != nullptr);
   
   DWORD windows_thread_id = 0;
@@ -206,23 +206,34 @@ internal bool thread_init (Thread* thread, Thread_Proc proc, string thread_name)
   // size of the starting arena and temp should be parameterized (+2 bytes)
   // make thread_init_ex with params...
   Arena* arena = next_arena(Arena_Reserve::Size_64G);
+  push_arena(arena);
   thread->context = New<Thread_Context>(get_allocator(arena));
   thread->context->temp        = next_arena(Arena_Reserve::Size_64G);
   thread->context->arena       = arena;
   thread->context->allocator   = get_allocator(arena);
   thread->context->thread_idx  = (s32)this_thread_index;
-  thread->context->thread_name = thread_name;
+  thread->context->thread_name = copy_string(thread_name);
   
   thread->os_thread.windows_thread    = windows_thread;
   thread->os_thread.windows_thread_id = windows_thread_id;
   
   thread->proc = proc;
   thread->index = this_thread_index;
-  // #TODO: prepare thread data
   
   return true;
 }
 
+internal void thread_deinit (Thread* thread) {
+  if (thread->os_thread.windows_thread) {
+    CloseHandle(thread->os_thread.windows_thread);
+  }
+  thread->os_thread.windows_thread = nullptr;
+  
+  // #TODO: Thread cleanup:
+  release_arena(thread->context->temp, true);
+  release_arena(thread->context->arena, true);
+}
+
 internal void thread_start (Thread* thread) {
   ResumeThread(thread->os_thread.windows_thread);
 }
@@ -234,10 +245,6 @@ internal bool thread_is_done (Thread* thread, s32 milliseconds=0) {
   return result != WAIT_TIMEOUT;
 }
 
-// Individual Threads
-
-// Thread Group API?
-
 // #thread_primitives
 internal void mutex_init (Mutex* mutex) {
   InitializeCriticalSection(&mutex->csection);
@@ -251,8 +258,7 @@ internal void lock (Mutex* mutex) {
 internal void unlock (Mutex* mutex) {
   LeaveCriticalSection(&mutex->csection);
 }
-internal void semaphore_init (Semaphore* sem, s32 initial_value = 0);
-internal void semaphore_init (Semaphore* sem, s32 initial_value) {
+internal void semaphore_init (Semaphore* sem, s32 initial_value = 0) {
   Assert(initial_value >= 0);
   sem->event = CreateSemaphoreW(nullptr, initial_value, 0x7fffffff, nullptr);
 }
@@ -269,8 +275,7 @@ enum class Wait_For_Result : s32 {
   ERROR = 2 // can't use ERROR because of Windows.h *sigh*
 };
 
-internal Wait_For_Result wait_for (Semaphore* sem, s32 milliseconds=-1);
-internal Wait_For_Result wait_for (Semaphore* sem, s32 milliseconds) {
+internal Wait_For_Result wait_for (Semaphore* sem, s32 milliseconds = -1) {
   DWORD res = 0;
   if (milliseconds < 0) {
     res = WaitForSingleObject(sem->event, INFINITE);
@@ -292,8 +297,7 @@ internal void condition_variable_init (Condition_Variable* cv) {
 internal void condition_variable_destroy (Condition_Variable* cv) {
   // No action required.
 }
-internal void wait (Condition_Variable* cv, Mutex* mutex, s32 wait_time_ms=-1);
-internal void wait (Condition_Variable* cv, Mutex* mutex, s32 wait_time_ms) {
+internal void wait (Condition_Variable* cv, Mutex* mutex, s32 wait_time_ms = -1) {
   SleepConditionVariableCS(&cv->condition_variable, &mutex->csection, (DWORD)wait_time_ms);
 }
 internal void wake (Condition_Variable* cv) {

lib_main.cpp

@@ -1,10 +1,10 @@
-// This is quite disorganized. There must be a better way to do this by moving the stuff that requires forward declaration to the top
-// with a metaprogram.
-
-
-// ~musa This is a unity build, where all source files in the project is combined into a single 
+// ~Musa - This is a unity build, where all source files in the project is combined into a single 
 // translation unit.
 // lib_main.cpp can be treated as a single-header library and added to a project like that.
+
+// #TODO: This is quite disorganized. There must be a better way to do this by moving the 
+// typedefs and procedures that require forward declaration to the top with a metaprogram.
+
 #include "lib/meta_generated.h"
 #include "lib/Base/Base.h"
 #include "lib/Base/Allocator.h"
@@ -24,16 +24,20 @@
 #include "lib/Base/Basic.cpp"
 
 // OS-Abstraction Layer
+#include "lib/Base/Threads.cpp"
 #include "lib/OS/Base_Entry_Point.cpp"
 
-// #if OS_LINUX..
-#include "lib/Base/Threads.cpp"
+
 #if OS_WINDOWS 
 # include "lib/OS/OS_Win32.cpp"
 #endif
 
+#include "lib/Base/Thread_Group.cpp"
+
 // #include "imgui-docking.cpp"
 
+// #if OS_LINUX..
 // #include "src/OS_Linux.cpp" // #TODO: Future.
+// #if OS_MACOS..
 // #include "src/OS_MacOS.cpp" // #TODO: Future.