LibCore: Port SharedCircularQueue to Windows

Author: https://github.com/stasoid
Commit: 777dcdf6d0
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2654
Reviewed-by: https://github.com/ADKaster ✅

Libraries/LibCore/SharedCircularQueue.h

@@ -1,33 +1,17 @@
 /*
  * Copyright (c) 2022, kleines Filmröllchen <filmroellchen@serenityos.org>
+ * Copyright (c) 2024, stasoid <stasoid@yahoo.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #pragma once
 
-#include <AK/Assertions.h>
-#include <AK/Atomic.h>
 #include <AK/BuiltinWrappers.h>
 #include <AK/ByteString.h>
 #include <AK/Debug.h>
-#include <AK/Error.h>
-#include <AK/Format.h>
 #include <AK/Function.h>
-#include <AK/NonnullRefPtr.h>
-#include <AK/NumericLimits.h>
-#include <AK/Platform.h>
-#include <AK/RefCounted.h>
-#include <AK/RefPtr.h>
-#include <AK/Types.h>
-#include <AK/Variant.h>
-#include <AK/Weakable.h>
 #include <LibCore/AnonymousBuffer.h>
-#include <LibCore/System.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <sched.h>
-#include <sys/mman.h>
 
 namespace Core {
 
@@ -64,14 +48,17 @@ public:
     // Allocates a new circular queue in shared memory.
     static ErrorOr<SharedSingleProducerCircularQueue<T, Size>> create()
     {
-        auto fd = TRY(System::anon_create(sizeof(SharedMemorySPCQ), O_CLOEXEC));
+        auto anon_buf = TRY(AnonymousBuffer::create_with_size(sizeof(SharedMemorySPCQ)));
-        return create_internal(fd, true);
+        auto shared_queue = new (anon_buf.data<void>()) SharedMemorySPCQ;
+        return create_internal(anon_buf, shared_queue);
     }
 
     // Uses an existing circular queue from given shared memory.
     static ErrorOr<SharedSingleProducerCircularQueue<T, Size>> create(int fd)
     {
-        return create_internal(fd, false);
+        auto anon_buf = TRY(AnonymousBuffer::create_from_anon_fd(fd, sizeof(SharedMemorySPCQ)));
+        auto shared_queue = (SharedMemorySPCQ*)anon_buf.data<void>();
+        return create_internal(anon_buf, shared_queue);
     }
 
     constexpr size_t size() const { return Size; }
@@ -84,7 +71,7 @@ public:
         return head - tail;
     }
 
-    ALWAYS_INLINE constexpr int fd() const { return m_queue->m_fd; }
+    ALWAYS_INLINE constexpr int fd() const { return m_queue->fd(); }
     ALWAYS_INLINE constexpr bool is_valid() const { return !m_queue.is_null(); }
 
     ALWAYS_INLINE constexpr size_t weak_head() const { return m_queue->m_queue->m_head.load(AK::MemoryOrder::memory_order_relaxed); }
@@ -174,42 +161,35 @@ private:
         alignas(ValueType) Array<ValueType, Size> m_data;
     };
 
-    class RefCountedSharedMemorySPCQ : public RefCounted<RefCountedSharedMemorySPCQ> {
+    class RefCountedSharedMemorySPCQ
+        : public RefCounted<RefCountedSharedMemorySPCQ>
+        , public AnonymousBuffer {
         friend class SharedSingleProducerCircularQueue;
 
     public:
         SharedMemorySPCQ* m_queue;
-        void* m_raw;
-        int m_fd;
 
         ~RefCountedSharedMemorySPCQ()
         {
-            MUST(System::close(m_fd));
+            dbgln_if(SHARED_QUEUE_DEBUG, "destructed SSPCQ at {:p}, shared mem: {:p}", this, m_queue);
-            MUST(System::munmap(m_raw, sizeof(SharedMemorySPCQ)));
-            dbgln_if(SHARED_QUEUE_DEBUG, "destructed SSPCQ at {:p}, shared mem: {:p}", this, this->m_raw);
         }
 
     private:
-        RefCountedSharedMemorySPCQ(SharedMemorySPCQ* queue, int fd)
+        RefCountedSharedMemorySPCQ(AnonymousBuffer anon_buf, SharedMemorySPCQ* shared_queue)
-            : m_queue(queue)
+            : AnonymousBuffer(anon_buf)
-            , m_raw(reinterpret_cast<void*>(queue))
+            , m_queue(shared_queue)
-            , m_fd(fd)
         {
         }
     };
 
-    static ErrorOr<SharedSingleProducerCircularQueue<T, Size>> create_internal(int fd, bool is_new)
+    static ErrorOr<SharedSingleProducerCircularQueue<T, Size>> create_internal(AnonymousBuffer anon_buf, SharedMemorySPCQ* shared_queue)
     {
-        auto name = ByteString::formatted("SharedSingleProducerCircularQueue@{:x}", fd);
-        auto* raw_mapping = TRY(System::mmap(nullptr, sizeof(SharedMemorySPCQ), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0, 0, name));
-        dbgln_if(SHARED_QUEUE_DEBUG, "successfully mmapped {} at {:p}", name, raw_mapping);
-
-        SharedMemorySPCQ* shared_queue = is_new ? new (raw_mapping) SharedMemorySPCQ() : reinterpret_cast<SharedMemorySPCQ*>(raw_mapping);
-
         if (!shared_queue)
             return Error::from_string_literal("Unexpected error when creating shared queue from raw memory");
-
+        auto name = ByteString::formatted("SharedSingleProducerCircularQueue@{:x}", anon_buf.fd());
-        return SharedSingleProducerCircularQueue<T, Size> { move(name), adopt_ref(*new (nothrow) RefCountedSharedMemorySPCQ(shared_queue, fd)) };
+        dbgln_if(SHARED_QUEUE_DEBUG, "successfully mmapped {} at {:p}", name, shared_queue);
+        auto ref_counted = new (nothrow) RefCountedSharedMemorySPCQ(anon_buf, shared_queue);
+        return SharedSingleProducerCircularQueue<T, Size> { move(name), adopt_ref(*ref_counted) };
     }
 
     SharedSingleProducerCircularQueue(ByteString name, RefPtr<RefCountedSharedMemorySPCQ> queue)