replace ArrayLists with bounded storage

1 files changed, 107 insertions, 5 deletions

diff --git a/src/pdf_bridge.c b/src/pdf_bridge.c
index e0969018..25870f20 100644
--- a/src/pdf_bridge.c
+++ b/src/pdf_bridge.c
@@ -5,12 +5,17 @@
 #include <math.h>
 #include <limits.h>
 #include <stdint.h>
+#include <stdatomic.h>
 #include <stdlib.h>
 #include <string.h>
 
 #define PARDES_PDF_INITIAL_RESULT_QUADS 64
 
 struct pardes_pdf_document {
+    pardes_pdf_allocator allocator;
+    fz_alloc_context mupdf_allocator;
+    int uses_allocator;
+
     fz_context *ctx;
     fz_document *doc;
     int page_count;
@@ -26,6 +31,97 @@ struct pardes_pdf_document {
     int display_list_candidate_page_number;
 };
 
+static pardes_pdf_allocator pardes_pdf_global_allocator;
+static int pardes_pdf_allocator_installed;
+static _Atomic size_t pardes_pdf_active_documents;
+static atomic_flag pardes_pdf_allocator_lock = ATOMIC_FLAG_INIT;
+
+static void
+pardes_pdf_lock_allocator(void)
+{
+    while (atomic_flag_test_and_set_explicit(
+        &pardes_pdf_allocator_lock, memory_order_acquire))
+        ;
+}
+
+static void
+pardes_pdf_unlock_allocator(void)
+{
+    atomic_flag_clear_explicit(
+        &pardes_pdf_allocator_lock, memory_order_release);
+}
+
+
+int
+pardes_pdf_set_allocator(const pardes_pdf_allocator *allocator)
+{
+    int status = PARDES_PDF_OK;
+
+    if (allocator != NULL &&
+        (allocator->alloc == NULL || allocator->realloc == NULL ||
+            allocator->free == NULL))
+        return PARDES_PDF_ERROR;
+
+    pardes_pdf_lock_allocator();
+    if (atomic_load(&pardes_pdf_active_documents) != 0) {
+        status = PARDES_PDF_ERROR;
+    } else if (allocator == NULL) {
+        memset(&pardes_pdf_global_allocator, 0,
+            sizeof(pardes_pdf_global_allocator));
+        pardes_pdf_allocator_installed = 0;
+    } else {
+        pardes_pdf_global_allocator = *allocator;
+        pardes_pdf_allocator_installed = 1;
+    }
+    pardes_pdf_unlock_allocator();
+    return status;
+}
+
+static pardes_pdf_document *
+pardes_pdf_allocate_document(void)
+{
+    pardes_pdf_document *document;
+    pardes_pdf_allocator allocator;
+    int uses_allocator;
+
+    pardes_pdf_lock_allocator();
+    uses_allocator = pardes_pdf_allocator_installed;
+    allocator = pardes_pdf_global_allocator;
+    atomic_fetch_add(&pardes_pdf_active_documents, 1);
+    pardes_pdf_unlock_allocator();
+
+    if (uses_allocator) {
+        document = (pardes_pdf_document *)allocator.alloc(
+            allocator.user, sizeof(*document));
+    } else {
+        document = (pardes_pdf_document *)calloc(1, sizeof(*document));
+    }
+    if (document == NULL) {
+        atomic_fetch_sub(&pardes_pdf_active_documents, 1);
+        return NULL;
+    }
+    if (!uses_allocator)
+        return document;
+
+    memset(document, 0, sizeof(*document));
+    document->allocator = allocator;
+    document->uses_allocator = 1;
+    document->mupdf_allocator.user = allocator.user;
+    document->mupdf_allocator.malloc = allocator.alloc;
+    document->mupdf_allocator.realloc = allocator.realloc;
+    document->mupdf_allocator.free = allocator.free;
+    return document;
+}
+
+static void
+pardes_pdf_free_document(pardes_pdf_document *document)
+{
+    if (document->uses_allocator)
+        document->allocator.free(document->allocator.user, document);
+    else
+        free(document);
+}
+
 static void
 pardes_pdf_drop_cached_page(pardes_pdf_document *document)
 {
@@ -230,15 +326,19 @@ pardes_pdf_open(const char *path, int *page_count)
     if (path == NULL || page_count == NULL)
         return NULL;
 
-    state = (pardes_pdf_document *)calloc(1, sizeof(*state));
+    state = pardes_pdf_allocate_document();
     if (state == NULL)
         return NULL;
     state->cached_page_number = -1;
     state->display_list_candidate_page_number = -1;
 
-    ctx = fz_new_context(NULL, NULL, PARDES_PDF_STORE_LIMIT_BYTES);
+    ctx = fz_new_context(
+        state->uses_allocator ? &state->mupdf_allocator : NULL,
+        NULL,
+        PARDES_PDF_STORE_LIMIT_BYTES);
     if (ctx == NULL) {
-        free(state);
+        pardes_pdf_free_document(state);
+        atomic_fetch_sub(&pardes_pdf_active_documents, 1);
         return NULL;
     }
 
@@ -256,7 +356,8 @@ pardes_pdf_open(const char *path, int *page_count)
         fz_report_error(ctx);
         fz_drop_document(ctx, doc);
         fz_drop_context(ctx);
-        free(state);
+        pardes_pdf_free_document(state);
+        atomic_fetch_sub(&pardes_pdf_active_documents, 1);
         return NULL;
     }
 
@@ -275,7 +376,8 @@ pardes_pdf_close(pardes_pdf_document *document)
     pardes_pdf_drop_cached_page(document);
     fz_drop_document(document->ctx, document->doc);
     fz_drop_context(document->ctx);
-    free(document);
+    pardes_pdf_free_document(document);
+    atomic_fetch_sub(&pardes_pdf_active_documents, 1);
 }
 
 int