a much more simplified version of push_back with reallocf instead of memcpy as it is faster (no copying just resizing the vector (entire point of vector))

2026-04-17 14:15:24 -04:00
parent c05e92dec0
commit b77f260a2c
9 changed files with 601 additions and 24 deletions
@@ -0,0 +1,108 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <mach/mach.h>
+#include <sys/resource.h>
+
+typedef struct {
+    char* arr;
+    size_t size;
+    size_t capacity;
+} Vec8_t;
+
+Vec8_t create(const Vec8_t* input) {
+    Vec8_t vec = { .arr = NULL, .size = 0, .capacity = 4 };
+    if (input == NULL) {
+        vec.arr = calloc(vec.capacity, sizeof(char));
+        return vec;
+    }
+    if (input->size > 0) {
+        vec.size = input->size + 1;
+    }
+    if (input->capacity >= vec.capacity) {
+        vec.capacity = 2 * input->capacity;
+    }
+    vec.arr = calloc(vec.capacity, sizeof(char));
+    return vec;
+}
+
+void delete(Vec8_t* vec) {
+    if (vec->arr != NULL) {
+        free(vec->arr);
+        vec->arr = NULL;
+    }
+    vec->size = 0;
+    vec->capacity = 0;
+}
+
+Vec8_t add_back(Vec8_t* vec, const char val) {
+    if (vec->size < vec->capacity) {
+        vec->arr[vec->size] = val;
+        vec->size++;
+        return *vec;
+    }
+    if (vec->size >= vec->capacity) {
+        Vec8_t nvec = create(vec);
+        if (nvec.arr == NULL) {
+            return *vec;
+        }
+        memcpy(&nvec.arr[0], &vec->arr[0], vec->size * sizeof(char));
+        if (nvec.arr && (nvec.size > 0 || nvec.size > vec->size)) {
+            nvec.arr[vec->size] = val;
+        }
+        free(vec->arr);
+        return nvec;
+    }
+    Vec8_t ret = { .arr = NULL, .capacity = 0, .size = 0 };
+    return ret;
+}
+
+vm_size_t get_physical_mem() {
+    struct task_basic_info info;
+    mach_msg_type_number_t count = TASK_BASIC_INFO_COUNT;
+    task_info(mach_task_self(), TASK_BASIC_INFO, (task_info_t)&info, &count);
+    return info.resident_size;
+}
+
+int main() {
+    printf("=== PHYSICAL MEMORY LEAK TEST ===\n\n");
+    
+    printf("Initial physical: %.2f MB\n", get_physical_mem() / 1024.0 / 1024.0);
+    
+    printf("\n--- Creating large vector ---\n");
+    Vec8_t big = create(NULL);
+    
+    printf("Adding elements...\n");
+    for (size_t i = 0; i < 100000000; i++) {
+        big = add_back(&big, 'x');
+        if (i % 10000000 == 0) {
+            printf("  %zu elements: %.2f MB\n", i+1, get_physical_mem() / 1024.0 / 1024.0);
+        }
+    }
+    
+    printf("  Final: %zu elements, %.2f MB\n", big.size, get_physical_mem() / 1024.0 / 1024.0);
+    
+    printf("\n--- BEFORE delete: %.2f MB ---\n", get_physical_mem() / 1024.0 / 1024.0);
+    
+    delete(&big);
+    
+    printf("--- AFTER delete: %.2f MB ---\n", get_physical_mem() / 1024.0 / 1024.0);
+    
+    printf("\n--- Create 1000 vectors then delete ---\n");
+    printf("Before: %.2f MB\n", get_physical_mem() / 1024.0 / 1024.0);
+    
+    for (int c = 0; c < 1000; c++) {
+        Vec8_t v = create(NULL);
+        for (int i = 0; i < 100000; i++) {
+            v = add_back(&v, 'x');
+        }
+        delete(&v);
+    }
+    
+    printf("After cycles: %.2f MB\n", get_physical_mem() / 1024.0 / 1024.0);
+    
+    printf("\n--- RESULT ---\n");
+    printf("Physical memory used: %.2f MB\n", get_physical_mem() / 1024.0 / 1024.0);
+    
+    return 0;
+}