Refactor: Pull stamped integer into own file.

lib/pls/CMakeLists.txt

@@ -22,6 +22,7 @@ add_library(pls STATIC
         include/pls/internal/data_structures/aligned_stack_impl.h
         include/pls/internal/data_structures/deque.h src/internal/data_structures/deque.cpp
         include/pls/internal/data_structures/work_stealing_deque.h include/pls/internal/data_structures/work_stealing_deque_impl.h
+        include/pls/internal/data_structures/stamped_integer.h
 
         include/pls/internal/helpers/prohibit_new.h
         include/pls/internal/helpers/profiler.h

lib/pls/include/pls/internal/data_structures/stamped_integer.h

+
+#ifndef PREDICTABLE_PARALLEL_PATTERNS_LIB_PLS_INCLUDE_PLS_INTERNAL_DATA_STRUCTURES_STAMPED_INTEGER_H_
+#define PREDICTABLE_PARALLEL_PATTERNS_LIB_PLS_INCLUDE_PLS_INTERNAL_DATA_STRUCTURES_STAMPED_INTEGER_H_
+
+#include "pls/internal/base/system_details.h"
+
+namespace pls {
+namespace internal {
+namespace data_structures {
+
+constexpr unsigned long HALF_CACHE_LINE = base::system_details::CACHE_LINE_SIZE / 2;
+struct stamped_integer {
+  using member_t = base::system_details::cas_integer;
+
+  member_t stamp:HALF_CACHE_LINE;
+  member_t value:HALF_CACHE_LINE;
+
+  stamped_integer() : stamp{0}, value{0} {};
+  stamped_integer(member_t new_value) : stamp{0}, value{new_value} {};
+  stamped_integer(member_t new_stamp, member_t new_value) : stamp{new_stamp}, value{new_value} {};
+};
+
+}
+}
+}
+
+#endif //PREDICTABLE_PARALLEL_PATTERNS_LIB_PLS_INCLUDE_PLS_INTERNAL_DATA_STRUCTURES_STAMPED_INTEGER_H_

lib/pls/include/pls/internal/data_structures/work_stealing_deque.h

@@ -4,9 +4,9 @@
 
 #include <atomic>
 
-#include "pls/internal/scheduling/thread_state.h"
-#include "pls/internal/base/system_details.h"
 #include "pls/internal/base/error_handling.h"
+#include "pls/internal/data_structures/stamped_integer.h"
+#include "pls/internal/scheduling/thread_state.h"
 
 #include "aligned_stack.h"
 
@@ -17,16 +17,8 @@ namespace data_structures {
 using base::system_details::pointer_t;
 
 // Integer split into two halfs, can be used in CAS operations
-constexpr unsigned long HALF_CACHE_LINE = base::system_details::CACHE_LINE_SIZE / 2;
-using offset_t = base::system_details::cas_integer;
-struct stamped_integer {
-  offset_t stamp:HALF_CACHE_LINE;
-  offset_t offset:HALF_CACHE_LINE;
-
-  stamped_integer() : stamp{0}, offset{0} {};
-  stamped_integer(offset_t new_offset) : stamp{0}, offset{new_offset} {};
-  stamped_integer(offset_t new_stamp, offset_t new_offset) : stamp{new_stamp}, offset{new_offset} {};
-};
+using data_structures::stamped_integer;
+using offset_t = stamped_integer::member_t;
 
 // Single Item in the deque
 class work_stealing_deque_item {

lib/pls/include/pls/internal/data_structures/work_stealing_deque_impl.h

@@ -61,7 +61,7 @@ Item *work_stealing_deque<Item>::pop_tail() {
   offset_t local_tail = tail_;
   stamped_integer local_head = head_;
 
-  if (local_tail <= local_head.offset) {
+  if (local_tail <= local_head.value) {
     return nullptr; // EMPTY
   }
 
@@ -74,11 +74,11 @@ Item *work_stealing_deque<Item>::pop_tail() {
   // Get the state of local head AFTER we published our wish
   local_head = head_; // Linearization point, outside knows list is empty
 
-  if (local_head.offset < new_tail) {
+  if (local_head.value < new_tail) {
     return previous_tail_item->data<Item>(); // Success, enough distance to other threads
   }
 
-  if (local_head.offset == new_tail) {
+  if (local_head.value == new_tail) {
     stamped_integer new_head = stamped_integer{local_head.stamp + 1, new_tail};
     // Try competing with consumers by updating the head's stamp value
     if (head_.compare_exchange_strong(local_head, new_head)) {
@@ -89,7 +89,7 @@ Item *work_stealing_deque<Item>::pop_tail() {
   // Some other thread either won the competition or it already set the head further than we are
   // before we even tried to compete with it.
   // Reset the queue into an empty state => head_ = tail_
-  tail_ = local_head.offset; // ...we give up to the other winning thread
+  tail_ = local_head.value; // ...we give up to the other winning thread
 
   return nullptr; // EMPTY, we lost the competition with other threads
 }
@@ -99,14 +99,14 @@ Item *work_stealing_deque<Item>::pop_head() {
   stamped_integer local_head = head_;
   offset_t local_tail = tail_;
 
-  if (local_tail <= local_head.offset) {
+  if (local_tail <= local_head.value) {
     return nullptr; // EMPTY
   }
   // Load info on current deque item.
   // In case we have a race with a new (aba) overwritten item at this position,
   // there has to be a competition over the tail -> the stamp increased and our next
   // operation will fail anyways!
-  work_stealing_deque_item *head_deque_item = item_at(local_head.offset);
+  work_stealing_deque_item *head_deque_item = item_at(local_head.value);
   offset_t next_item_offset = head_deque_item->next_item();
   Item *head_data_item = head_deque_item->data<Item>();
 
@@ -134,7 +134,7 @@ void work_stealing_deque<Item>::release_memory_until(state state) {
 
   if (item_offset < local_tail) {
     tail_ = item_offset;
-    if (local_head.offset >= local_tail) {
+    if (local_head.value >= local_tail) {
       head_ = stamped_integer{local_head.stamp + 1, item_offset};
     }
   }