1 files changed, 98 insertions, 0 deletions
diff --git a/src/core/lib/support/arena.c b/src/core/lib/support/arena.c
new file mode 100644
index 0000000000..7bcb983f24
--- /dev/null
+++ b/src/core/lib/support/arena.c
@@ -0,0 +1,98 @@
+/*
+ *
+ * Copyright 2017, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/support/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_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 == NULL) {
+      size_t next_z_size = (size_t)gpr_atm_no_barrier_load(&arena->size_so_far);
+      next_z = 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;
+}