1 files changed, 83 insertions, 0 deletions
diff --git a/src/core/lib/gpr/arena.cc b/src/core/lib/gpr/arena.cc
new file mode 100644
index 0000000000..177c176732
--- /dev/null
+++ b/src/core/lib/gpr/arena.cc
@@ -0,0 +1,83 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include "src/core/lib/gpr/arena.h"
+#include <grpc/support/alloc.h>
+#include <grpc/support/atm.h>
+#include <grpc/support/log.h>
+#include <grpc/support/useful.h>
+
+#define ROUND_UP_TO_ALIGNMENT_SIZE(x) \
+  (((x) + GPR_MAX_ALIGNMENT - 1u) & ~(GPR_MAX_ALIGNMENT - 1u))
+
+typedef struct zone {
+  size_t size_begin;
+  size_t size_end;
+  gpr_atm next_atm;
+} zone;
+
+struct gpr_arena {
+  gpr_atm size_so_far;
+  zone initial_zone;
+};
+
+gpr_arena* gpr_arena_create(size_t initial_size) {
+  initial_size = ROUND_UP_TO_ALIGNMENT_SIZE(initial_size);
+  gpr_arena* a = (gpr_arena*)gpr_zalloc(sizeof(gpr_arena) + initial_size);
+  a->initial_zone.size_end = initial_size;
+  return a;
+}
+
+size_t gpr_arena_destroy(gpr_arena* arena) {
+  gpr_atm size = gpr_atm_no_barrier_load(&arena->size_so_far);
+  zone* z = (zone*)gpr_atm_no_barrier_load(&arena->initial_zone.next_atm);
+  gpr_free(arena);
+  while (z) {
+    zone* next_z = (zone*)gpr_atm_no_barrier_load(&z->next_atm);
+    gpr_free(z);
+    z = next_z;
+  }
+  return (size_t)size;
+}
+
+void* gpr_arena_alloc(gpr_arena* arena, size_t size) {
+  size = ROUND_UP_TO_ALIGNMENT_SIZE(size);
+  size_t start =
+      (size_t)gpr_atm_no_barrier_fetch_add(&arena->size_so_far, size);
+  zone* z = &arena->initial_zone;
+  while (start > z->size_end) {
+    zone* next_z = (zone*)gpr_atm_acq_load(&z->next_atm);
+    if (next_z == nullptr) {
+      size_t next_z_size = (size_t)gpr_atm_no_barrier_load(&arena->size_so_far);
+      next_z = (zone*)gpr_zalloc(sizeof(zone) + next_z_size);
+      next_z->size_begin = z->size_end;
+      next_z->size_end = z->size_end + next_z_size;
+      if (!gpr_atm_rel_cas(&z->next_atm, (gpr_atm)NULL, (gpr_atm)next_z)) {
+        gpr_free(next_z);
+        next_z = (zone*)gpr_atm_acq_load(&z->next_atm);
+      }
+    }
+    z = next_z;
+  }
+  if (start + size > z->size_end) {
+    return gpr_arena_alloc(arena, size);
+  }
+  GPR_ASSERT(start >= z->size_begin);
+  GPR_ASSERT(start + size <= z->size_end);
+  return ((char*)(z + 1)) + start - z->size_begin;
+}