[memory] Testdrive a delayed flushing in FlushableMemory

thoni56 · Jan 31, 2025 · 9072a6d · 9072a6d
1 parent 067f7bd
commit 9072a6d
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Showing 3 changed files with 62 additions and 1 deletion.
diff --git a/src/memory.c b/src/memory.c
@@ -252,6 +252,7 @@ void initFlushableMemory(FlushableMemory *memory) {
     memory->size = 0;
     memory->top = 0;
     memory->blocks = NULL;
+    memory->pendingFlushIndex = -1;
 }
 
 void *allocateFlushableMemory(FlushableMemory *memory, size_t size) {
@@ -283,3 +284,30 @@ bool flushableMemoryIsFreed(FlushableMemory *memory, void *pointer) {
             return true;
     return false;
 }
+
+void markAsFlushable(FlushableMemory *memory, void *pointer) {
+    for (int i=memory->top; i >= 0; i--) {
+        if (memory->blocks[i] == pointer) {
+            memory->pendingFlushIndex = i;
+            return;
+        }
+    }
+    assert(0);
+}
+
+bool memoryWouldBeFlushed(FlushableMemory *memory, void *pointer) {
+    if (memory->pendingFlushIndex == -1)
+        return false;           /* No flush pending */
+
+    for (int i=0; i < memory->pendingFlushIndex && i <= memory->top; i++)
+        if (memory->blocks[i] == pointer)
+            return false;
+    return true;
+}
+
+void flushPendingMemory(FlushableMemory *memory) {
+    for (int i=memory->pendingFlushIndex; i <= memory->top; i++) {
+        free(memory->blocks[i]);
+        memory->blocks[i] = NULL;
+    }
+}
diff --git a/src/memory.h b/src/memory.h
@@ -65,19 +65,23 @@ extern bool cxMemoryIsFreed(void *pointer);
 extern bool cxMemoryOverflowHandler(int n);
 
 /***********************************************************************/
-/* New, so far, unused new Memory handling */
+/* New, so far unused, new Memory handling */
 
 #define DONT_USE_NEW_CXMEMORY
 
 typedef struct {
     int size;
     int top;
     void **blocks;
+    int pendingFlushIndex;
 } FlushableMemory;
 
 extern void initFlushableMemory(FlushableMemory *memory);
 extern void *allocateFlushableMemory(FlushableMemory *memory, size_t size);
 extern void freeFlushableMemoryUntil(FlushableMemory *memory, void *pointer);
 extern bool flushableMemoryIsFreed(FlushableMemory *memory, void *pointer);
+extern bool memoryWouldBeFlushed(FlushableMemory *memory, void *pointer);
+extern void markAsFlushable(FlushableMemory *memory, void *pointer);
+extern void flushPendingMemory(FlushableMemory *memory);
 
 #endif
diff --git a/src/memory_tests.c b/src/memory_tests.c
@@ -246,3 +246,32 @@ Ensure(Memory, can_see_if_flushable_memory_is_freed) {
     assert_that(flushableMemoryIsFreed(&memory, c));
     assert_that(flushableMemoryIsFreed(&memory, d));
 }
+
+Ensure(Memory, can_mark_flushable_memory_for_flushing) {
+    FlushableMemory memory;
+
+    initFlushableMemory(&memory);
+
+    void *a = allocateFlushableMemory(&memory, 4);
+    void *b = allocateFlushableMemory(&memory, 4);
+    void *c = allocateFlushableMemory(&memory, 4);
+    void *d = allocateFlushableMemory(&memory, 4);
+
+    assert_that(!memoryWouldBeFlushed(&memory, a));
+    assert_that(!memoryWouldBeFlushed(&memory, b));
+    assert_that(!memoryWouldBeFlushed(&memory, c));
+    assert_that(!memoryWouldBeFlushed(&memory, d));
+
+    markAsFlushable(&memory, b);
+    assert_that(!memoryWouldBeFlushed(&memory, a));
+    assert_that(memoryWouldBeFlushed(&memory, b));
+    assert_that(memoryWouldBeFlushed(&memory, c));
+    assert_that(memoryWouldBeFlushed(&memory, d));
+
+    flushPendingMemory(&memory);
+    assert_that(memory.blocks[0], is_not_null);
+    assert_that(memory.blocks[1], is_null);
+    assert_that(memory.blocks[2], is_null);
+    assert_that(memory.blocks[3], is_null);
+
+}