From 4080e7b65ff00e0c6d0edd743cb6ee4550c10048 Mon Sep 17 00:00:00 2001
From: Soheil Hassas Yeganeh <soheil@google.com>
Date: Wed, 17 Apr 2019 15:26:07 -0400
Subject: [PATCH] Retire the GRPC_ARENA_INIT_STRATEGY env variable.

This is in the hot path and it is not needed anymore.
Remove it for good.
---
 doc/environment_variables.md | 10 --------
 src/core/lib/gpr/arena.cc    | 50 ++++--------------------------------
 src/core/lib/gpr/arena.h     |  2 --
 src/core/lib/surface/init.cc |  1 -
 4 files changed, 5 insertions(+), 58 deletions(-)

diff --git a/doc/environment_variables.md b/doc/environment_variables.md
index e8d0dbd25f8..43dcd7616e7 100644
--- a/doc/environment_variables.md
+++ b/doc/environment_variables.md
@@ -145,13 +145,3 @@ some configuration as environment variables that can be set.
 * grpc_cfstream
   set to 1 to turn on CFStream experiment. With this experiment gRPC uses CFStream API to make TCP
   connections. The option is only available on iOS platform and when macro GRPC_CFSTREAM is defined.
-
-* GRPC_ARENA_INIT_STRATEGY
-  Selects the initialization strategy for blocks allocated in the arena. Valid
-  values are:
-  - no_init (default): Do not initialize the arena block.
-  - zero_init: Initialize the arena blocks with 0.
-  - non_zero_init: Initialize the arena blocks with a non-zero value.
-
-  NOTE: This environment variable is experimental and will be removed. Thus, it
-        should not be relied upon.
diff --git a/src/core/lib/gpr/arena.cc b/src/core/lib/gpr/arena.cc
index 836a7ca793d..ede5cc48050 100644
--- a/src/core/lib/gpr/arena.cc
+++ b/src/core/lib/gpr/arena.cc
@@ -29,49 +29,10 @@
 #include <grpc/support/sync.h>
 
 #include "src/core/lib/gpr/alloc.h"
-#include "src/core/lib/gpr/env.h"
 #include "src/core/lib/gprpp/memory.h"
 
-namespace {
-enum init_strategy {
-  NO_INIT,        // Do not initialize the arena blocks.
-  ZERO_INIT,      // Initialize arena blocks with 0.
-  NON_ZERO_INIT,  // Initialize arena blocks with a non-zero value.
-};
-
-gpr_once g_init_strategy_once = GPR_ONCE_INIT;
-init_strategy g_init_strategy = NO_INIT;
-}  // namespace
-
-static void set_strategy_from_env() {
-  char* str = gpr_getenv("GRPC_ARENA_INIT_STRATEGY");
-  if (str == nullptr) {
-    g_init_strategy = NO_INIT;
-  } else if (strcmp(str, "zero_init") == 0) {
-    g_init_strategy = ZERO_INIT;
-  } else if (strcmp(str, "non_zero_init") == 0) {
-    g_init_strategy = NON_ZERO_INIT;
-  } else {
-    g_init_strategy = NO_INIT;
-  }
-  gpr_free(str);
-}
-
-static void* gpr_arena_alloc_maybe_init(size_t size) {
-  void* mem = gpr_malloc_aligned(size, GPR_MAX_ALIGNMENT);
-  gpr_once_init(&g_init_strategy_once, set_strategy_from_env);
-  if (GPR_UNLIKELY(g_init_strategy != NO_INIT)) {
-    if (g_init_strategy == ZERO_INIT) {
-      memset(mem, 0, size);
-    } else {  // NON_ZERO_INIT.
-      memset(mem, 0xFE, size);
-    }
-  }
-  return mem;
-}
-
-void gpr_arena_init() {
-  gpr_once_init(&g_init_strategy_once, set_strategy_from_env);
+static void* gpr_arena_malloc(size_t size) {
+  return gpr_malloc_aligned(size, GPR_MAX_ALIGNMENT);
 }
 
 // Uncomment this to use a simple arena that simply allocates the
@@ -109,8 +70,7 @@ void* gpr_arena_alloc(gpr_arena* arena, size_t size) {
   gpr_mu_lock(&arena->mu);
   arena->ptrs =
       (void**)gpr_realloc(arena->ptrs, sizeof(void*) * (arena->num_ptrs + 1));
-  void* retval = arena->ptrs[arena->num_ptrs++] =
-      gpr_arena_alloc_maybe_init(size);
+  void* retval = arena->ptrs[arena->num_ptrs++] = gpr_arena_malloc(size);
   gpr_mu_unlock(&arena->mu);
   return retval;
 }
@@ -154,7 +114,7 @@ struct gpr_arena {
 
 gpr_arena* gpr_arena_create(size_t initial_size) {
   initial_size = GPR_ROUND_UP_TO_ALIGNMENT_SIZE(initial_size);
-  return new (gpr_arena_alloc_maybe_init(
+  return new (gpr_arena_malloc(
       GPR_ROUND_UP_TO_ALIGNMENT_SIZE(sizeof(gpr_arena)) + initial_size))
       gpr_arena(initial_size);
 }
@@ -179,7 +139,7 @@ void* gpr_arena_alloc(gpr_arena* arena, size_t size) {
     // sizing historesis (that is, most calls should have a large enough initial
     // zone and will not need to grow the arena).
     gpr_mu_lock(&arena->arena_growth_mutex);
-    zone* z = new (gpr_arena_alloc_maybe_init(
+    zone* z = new (gpr_arena_malloc(
         GPR_ROUND_UP_TO_ALIGNMENT_SIZE(sizeof(zone)) + size)) zone();
     arena->last_zone->next = z;
     arena->last_zone = z;
diff --git a/src/core/lib/gpr/arena.h b/src/core/lib/gpr/arena.h
index 069892b2282..6d2a073dd58 100644
--- a/src/core/lib/gpr/arena.h
+++ b/src/core/lib/gpr/arena.h
@@ -37,7 +37,5 @@ gpr_arena* gpr_arena_create(size_t initial_size);
 void* gpr_arena_alloc(gpr_arena* arena, size_t size);
 // Destroy an arena, returning the total number of bytes allocated
 size_t gpr_arena_destroy(gpr_arena* arena);
-// Initializes the Arena component.
-void gpr_arena_init();
 
 #endif /* GRPC_CORE_LIB_GPR_ARENA_H */
diff --git a/src/core/lib/surface/init.cc b/src/core/lib/surface/init.cc
index 57d975564b1..1ed1a66b184 100644
--- a/src/core/lib/surface/init.cc
+++ b/src/core/lib/surface/init.cc
@@ -133,7 +133,6 @@ void grpc_init(void) {
     }
     grpc_core::Fork::GlobalInit();
     grpc_fork_handlers_auto_register();
-    gpr_arena_init();
     grpc_stats_init();
     grpc_slice_intern_init();
     grpc_mdctx_global_init();