[Heap Trace Standalone] fix terrible Leaks perf on large records by using doubly linked list

components/heap/heap_trace_standalone.c

@@ -14,6 +14,7 @@
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
 #include "esp_memory_utils.h"
+#include "sys/queue.h"
 
 
 #define STACK_DEPTH CONFIG_HEAP_TRACING_STACK_DEPTH
@@ -24,15 +25,26 @@ static portMUX_TYPE trace_mux = portMUX_INITIALIZER_UNLOCKED;
 static bool tracing;
 static heap_trace_mode_t mode;
 
+/* Define struct: linked list of records */
+TAILQ_HEAD(heap_trace_record_list_struct_t, heap_trace_record_struct_t);
+typedef struct heap_trace_record_list_struct_t heap_trace_record_list_t;
+
+/* Linked List of Records */
 typedef struct {
 
-    /* Buffer used for records, starting at offset 0 */
+    /* Buffer used for records. */
     heap_trace_record_t *buffer;
 
+    /* Linked list of recorded allocations */
+    heap_trace_record_list_t list;
+
+    /* Linked list of available record objects */
+    heap_trace_record_list_t unused;
+
     /* capacity of the buffer */
     size_t capacity;
 
-    /* Count of entries logged in the buffer.*/
+    /* Count of entries logged in the buffer. */
     size_t count;
 
     /* During execution, we remember the maximum
@@ -46,8 +58,13 @@ typedef struct {
 
 
 // Forward Defines
-static void remove_record(records_t *r, int index);
 static void heap_trace_dump_base(bool internal_ram, bool psram);
+static void linked_list_setup();
+static void linked_list_remove(heap_trace_record_t* rRemove);
+static void linked_list_deep_copy(heap_trace_record_t *rDest, const heap_trace_record_t* rSrc);
+static bool linked_list_add(const heap_trace_record_t* rAppend);
+static heap_trace_record_t* linked_list_pop_unused();
+static heap_trace_record_t* linked_list_find_address_reverse(void* p);
 
 /* The actual records. */
 static records_t records;
@@ -64,9 +81,16 @@ esp_err_t heap_trace_init_standalone(heap_trace_record_t *record_buffer, size_t
         return ESP_ERR_INVALID_STATE;
     }
 
+    if (num_records == 0) {
+        return ESP_ERR_INVALID_ARG;
+    }
+
+    if (record_buffer == NULL) {
+        return ESP_ERR_INVALID_ARG;
+    }
+
     records.buffer = record_buffer;
     records.capacity = num_records;
-    memset(records.buffer, 0, num_records * sizeof(heap_trace_record_t));
 
     return ESP_OK;
 }
@@ -77,14 +101,17 @@ esp_err_t heap_trace_start(heap_trace_mode_t mode_param)
         return ESP_ERR_INVALID_STATE;
     }
 
-
     portENTER_CRITICAL(&trace_mux);
 
     tracing = false;
     mode = mode_param;
 
+    // clear buffer
+    memset(records.buffer, 0, sizeof(heap_trace_record_t) * records.capacity);
+
     records.count = 0;
     records.has_overflowed = false;
+    linked_list_setup(&records);
 
     total_allocations = 0;
     total_frees = 0;
@@ -118,9 +145,9 @@ size_t heap_trace_get_count(void)
     return records.count;
 }
 
-esp_err_t heap_trace_get(size_t index, heap_trace_record_t *record)
+esp_err_t heap_trace_get(size_t index, heap_trace_record_t *rOut)
 {
-    if (record == NULL) {
+    if (rOut == NULL) {
         return ESP_ERR_INVALID_STATE;
     }
 
@@ -129,9 +156,29 @@ esp_err_t heap_trace_get(size_t index, heap_trace_record_t *record)
     portENTER_CRITICAL(&trace_mux);
 
     if (index >= records.count) {
+
         result = ESP_ERR_INVALID_ARG; /* out of range for 'count' */
+
     } else {
-        memcpy(record, &records.buffer[index], sizeof(heap_trace_record_t));
+
+        // Iterate through through the linked list
+
+        heap_trace_record_t* rCur = TAILQ_FIRST(&records.list);
+
+        for (int i = 0; i < index; i++) {
+
+            // this should not happen, since we already
+            // checked that index >= records.count == false
+            if (rCur == NULL) {
+                result = ESP_ERR_INVALID_STATE;
+                break;
+            }
+
+            rCur = TAILQ_NEXT(rCur, tailq);
+        }
+
+        // copy to destination
+        memcpy(rOut, rCur, sizeof(heap_trace_record_t));
     }
 
     portEXIT_CRITICAL(&trace_mux);
@@ -167,6 +214,8 @@ void heap_trace_dump_caps(const uint32_t caps) {
 
 static void heap_trace_dump_base(bool internal_ram, bool psram)
 {
+    portENTER_CRITICAL(&trace_mux);
+
     size_t delta_size = 0;
     size_t delta_allocs = 0;
     size_t start_count = records.count;
@@ -174,45 +223,55 @@ static void heap_trace_dump_base(bool internal_ram, bool psram)
     printf("====== Heap Trace: %u records (%u capacity) ======\n",
         records.count, records.capacity);
 
+    // Iterate through through the linked list
+
+    heap_trace_record_t *rCur = TAILQ_FIRST(&records.list);
+
     for (int i = 0; i < records.count; i++) {
 
-        heap_trace_record_t *rec = &records.buffer[i];
+        // check corruption
+        if (rCur == NULL) {
+            printf("\nError: heap trace linked list is corrupt. expected more records.\n");
+            break;
+        }
 
-        bool should_print = rec->address != NULL &&
+        bool should_print = rCur->address != NULL &&
             ((psram && internal_ram) ||
-             (internal_ram && esp_ptr_internal(rec->address)) ||
+             (internal_ram && esp_ptr_internal(rCur->address)) ||
-             (psram && esp_ptr_external_ram(rec->address)));
+             (psram && esp_ptr_external_ram(rCur->address)));
 
         if (should_print) {
 
             const char* label = "";
-            if (esp_ptr_internal(rec->address)) {
+            if (esp_ptr_internal(rCur->address)) {
                 label = ", Internal";
             }
-            if (esp_ptr_external_ram(rec->address)) {
+            if (esp_ptr_external_ram(rCur->address)) {
                 label = ",    PSRAM";
             }
 
             printf("%6d bytes (@ %p%s) allocated CPU %d ccount 0x%08x caller ",
-                   rec->size, rec->address, label, rec->ccount & 1, rec->ccount & ~3);
+                   rCur->size, rCur->address, label, rCur->ccount & 1, rCur->ccount & ~3);
 
-            for (int j = 0; j < STACK_DEPTH && rec->alloced_by[j] != 0; j++) {
+            for (int j = 0; j < STACK_DEPTH && rCur->alloced_by[j] != 0; j++) {
-                printf("%p%s", rec->alloced_by[j],
+                printf("%p%s", rCur->alloced_by[j],
                        (j < STACK_DEPTH - 1) ? ":" : "");
             }
 
-            if (mode != HEAP_TRACE_ALL || STACK_DEPTH == 0 || rec->freed_by[0] == NULL) {
+            if (mode != HEAP_TRACE_ALL || STACK_DEPTH == 0 || rCur->freed_by[0] == NULL) {
-                delta_size += rec->size;
+                delta_size += rCur->size;
                 delta_allocs++;
                 printf("\n");
             } else {
                 printf("\nfreed by ");
                 for (int j = 0; j < STACK_DEPTH; j++) {
-                    printf("%p%s", rec->freed_by[j],
+                    printf("%p%s", rCur->freed_by[j],
                            (j < STACK_DEPTH - 1) ? ":" : "\n");
                 }
             }
         }
+
+        rCur = TAILQ_NEXT(rCur, tailq);
     }
 
     printf("====== Heap Trace Summary ======\n");
@@ -239,12 +298,14 @@ static void heap_trace_dump_base(bool internal_ram, bool psram)
         printf("(NB: Internal Buffer has overflowed, so trace data is incomplete.)\n");
     }
     printf("================================\n");
+
+    portEXIT_CRITICAL(&trace_mux);
 }
 
 /* Add a new allocation to the heap trace records */
-static IRAM_ATTR void record_allocation(const heap_trace_record_t *record)
+static IRAM_ATTR void record_allocation(const heap_trace_record_t *rAllocation)
 {
-    if (!tracing || record->address == NULL) {
+    if (!tracing || rAllocation->address == NULL) {
         return;
     }
 
@@ -252,34 +313,19 @@ static IRAM_ATTR void record_allocation(const heap_trace_record_t *record)
 
     if (tracing) {
 
+        // If buffer is full, pop off the oldest
+        // record to make more space
         if (records.count == records.capacity) {
 
             records.has_overflowed = true;
 
-            /* Move the whole buffer back one slot.
+            heap_trace_record_t *rFirst = TAILQ_FIRST(&records.list);
 
-            This is a bit slow, compared to treating this buffer as a
+            linked_list_remove(rFirst);
-            ringbuffer and rotating a head pointer.
-
-            However, ringbuffer code gets tricky when we remove elements
-            in mid-buffer (for leak trace mode) while trying to keep
-            track of an item count that may overflow.
-            */
-            memmove(&records.buffer[0], &records.buffer[1],
-                sizeof(heap_trace_record_t) * (records.capacity -1));
-
-            records.count--;
         }
 
-        // Copy new record into place
+        // push onto end of list
-        memcpy(&records.buffer[records.count], record, sizeof(heap_trace_record_t));
+        linked_list_add(rAllocation);
-
-        records.count++;
-
-        // high water mark
-        if (records.count > records.high_water_mark) {
-            records.high_water_mark = records.count;
-        }
 
         total_allocations++;
     }
@@ -304,25 +350,20 @@ static IRAM_ATTR void record_free(void *p, void **callers)
 
         total_frees++;
 
-        /* search backwards for the allocation record matching this free */
+        // search backwards for the allocation record matching this free
-        int i = -1;
+        heap_trace_record_t* rFound = linked_list_find_address_reverse(p);
-        for (i = records.count - 1; i >= 0; i--) {
-            if (records.buffer[i].address == p) {
-                break;
-            }
-        }
 
-        if (i >= 0) {
+        if (rFound) {
             if (mode == HEAP_TRACE_ALL) {
 
                 // add 'freed_by' info to the record
-                memcpy(records.buffer[i].freed_by, callers, sizeof(void *) * STACK_DEPTH);
+                memcpy(rFound->freed_by, callers, sizeof(void *) * STACK_DEPTH);
 
             } else { // HEAP_TRACE_LEAKS
 
                 // Leak trace mode, once an allocation is freed
                 // we remove it from the list
-                remove_record(&records, i);
+                linked_list_remove(rFound);
             }
         }
     }
@@ -330,18 +371,126 @@ static IRAM_ATTR void record_free(void *p, void **callers)
     portEXIT_CRITICAL(&trace_mux);
 }
 
-/* remove the entry at 'index' from the ringbuffer of saved records */
+// connect all records into a linked list of 'unused' records
-static IRAM_ATTR void remove_record(records_t *r, int index)
+static void linked_list_setup()
 {
-    if (index < r->count - 1) {
+    TAILQ_INIT(&records.list);
-        // Remove the buffer entry from the list
+    TAILQ_INIT(&records.unused);
-        memmove(&r->buffer[index], &r->buffer[index+1],
+
-                sizeof(heap_trace_record_t) * (r->capacity - index - 1));
+    for (int i = 0; i < records.capacity; i++) {
-    } else {
+
-        // For last element, just zero it out to avoid ambiguity
+        heap_trace_record_t* rCur = &records.buffer[i];
-        memset(&r->buffer[index], 0, sizeof(heap_trace_record_t));
+
+        TAILQ_INSERT_HEAD(&records.unused, rCur, tailq);
     }
-    r->count--;
+}
+
+/* 1. removes record from records.list,
+   2. places it into records.unused */
+static IRAM_ATTR void linked_list_remove(heap_trace_record_t* rRemove)
+{
+    assert(records.count > 0);
+
+    // remove from records.list
+    TAILQ_REMOVE(&records.list, rRemove, tailq);
+
+    // set as unused
+    rRemove->address = 0;
+    rRemove->size = 0;
+
+    // add to records.unused
+    TAILQ_INSERT_HEAD(&records.unused, rRemove, tailq);
+
+    // decrement
+    records.count--;
+}
+
+
+// pop record from unused list
+static IRAM_ATTR heap_trace_record_t* linked_list_pop_unused()
+{
+    // no records left?
+    if (records.count >= records.capacity) {
+        return NULL;
+    }
+
+    // get from records.unused
+    heap_trace_record_t* rUnused = TAILQ_FIRST(&records.unused);
+    assert(rUnused->address == NULL);
+    assert(rUnused->size == 0);
+
+    // remove from records.unused
+    TAILQ_REMOVE(&records.unused, rUnused, tailq);
+
+    return rUnused;
+}
+
+// deep copy a record.
+// Note: only copies the *allocation data*, not the next & prev ptrs
+static IRAM_ATTR void linked_list_deep_copy(heap_trace_record_t *rDest, const heap_trace_record_t *rSrc)
+{
+    rDest->ccount  = rSrc->ccount;
+    rDest->address = rSrc->address;
+    rDest->size    = rSrc->size;
+    memcpy(rDest->freed_by,   rSrc->freed_by,   sizeof(void *) * STACK_DEPTH);
+    memcpy(rDest->alloced_by, rSrc->alloced_by, sizeof(void *) * STACK_DEPTH);
+}
+
+// Append a record to records.list
+// Note: This deep copies rAppend
+static IRAM_ATTR bool linked_list_add(const heap_trace_record_t *rAppend)
+{
+    if (records.count < records.capacity) {
+
+        // get unused record
+        heap_trace_record_t* rDest = linked_list_pop_unused();
+
+        // we checked that there is capacity, so this
+        // should never be null.
+        assert(rDest != NULL);
+
+        // copy allocation data
+        linked_list_deep_copy(rDest, rAppend);
+
+        // append to records.list
+        TAILQ_INSERT_TAIL(&records.list, rDest, tailq);
+
+        // increment
+        records.count++;
+
+        // high water mark
+        if (records.count > records.high_water_mark) {
+            records.high_water_mark = records.count;
+        }
+
+        return true;
+
+    } else {
+        records.has_overflowed = true;
+        return false;
+    }
+}
+
+// search records.list backwards for the allocation record matching this address
+static IRAM_ATTR heap_trace_record_t* linked_list_find_address_reverse(void* p)
+{
+    if (records.count == 0) {
+        return NULL;
+    }
+
+    heap_trace_record_t* rFound = NULL;
+
+    // Perf: We search backwards because new allocations are appended
+    // to the end of the list and most allocations are short lived.
+    heap_trace_record_t *rCur = NULL;
+    TAILQ_FOREACH_REVERSE(rCur, &records.list, heap_trace_record_list_struct_t, tailq) {
+        if (rCur->address == p) {
+            rFound = rCur;
+            break;
+        }
+    }
+
+    return rFound;
 }
 
 #include "heap_trace.inc"

components/heap/include/esp_heap_trace.h

@@ -6,6 +6,7 @@
 #pragma once
 
 #include "sdkconfig.h"
+#include "sys/queue.h"
 #include <stdint.h>
 #include <esp_err.h>
 
@@ -29,13 +30,16 @@ typedef enum {
 /**
  * @brief Trace record data type. Stores information about an allocated region of memory.
  */
-typedef struct {
+struct heap_trace_record_struct_t {
     uint32_t ccount; ///< CCOUNT of the CPU when the allocation was made. LSB (bit value 1) is the CPU number (0 or 1).
-    void *address;   ///< Address which was allocated
+    void *address;   ///< Address which was allocated. If NULL, then this record is empty.
     size_t size;     ///< Size of the allocation
     void *alloced_by[CONFIG_HEAP_TRACING_STACK_DEPTH]; ///< Call stack of the caller which allocated the memory.
     void *freed_by[CONFIG_HEAP_TRACING_STACK_DEPTH];   ///< Call stack of the caller which freed the memory (all zero if not freed.)
-} heap_trace_record_t;
+    TAILQ_ENTRY(heap_trace_record_struct_t) tailq; ///< Linked list: prev & next records
+};
+
+typedef struct heap_trace_record_struct_t heap_trace_record_t;
 
 /**
  * @brief Stores information about the result of a heap trace.