Make inaccessible instead of null the default state of IC

Summary:
After reviewing the strobelight data from Swayze, it is clear that the memoizations got a lot more expensive after the previous changes.

The main theory behind that is, now null and inaccessible contexts create 2 separate shards in the memo caches (before it was just null) depending on the calling context.

This diff makes Inaccessible as the default context. IC is not set null from anywhere. If it's needed, it can be implemented later via a www backdoor

Reviewed By: jano

Differential Revision: D57356181

fbshipit-source-id: c14f16adf5f5f116dbe8fc968d0ada8ff95652f2

hphp/hack/src/hackc/emitter/emit_expression.rs

@@ -2970,6 +2970,9 @@ fn get_call_builtin_func_info(
         "HH\\ImplicitContext\\_Private\\set_implicit_context_by_value" if e.systemlib() => {
             Some((1, Instruct::Opcode(Opcode::SetImplicitContextByValue)))
         }
+        "HH\\ImplicitContext\\_Private\\get_inaccessible_implicit_context" if e.systemlib() => {
+            Some((0, Instruct::Opcode(Opcode::GetInaccessibleImplicitContext)))
+        }
         // TODO: enforce that this returns readonly
         "HH\\global_readonly_get" => Some((1, Instruct::Opcode(Opcode::CGetG))),
         "HH\\global_get" => Some((1, Instruct::Opcode(Opcode::CGetG))),

hphp/runtime/base/execution-context.cpp

@@ -653,8 +653,8 @@ void ExecutionContext::executeFunctions(ShutdownType type) {
       Cfg::Server::PspCpuTimeoutSeconds
   );
 
-  // Implicit context should not have leaked
-  assertx(!(*ImplicitContext::activeCtx));
+  // Since inaccessible is now used as the default context
+  assertx((*ImplicitContext::activeCtx) == (*ImplicitContext::inaccessibleCtx));
 
   // We mustn't destroy any callbacks until we're done with all
   // of them. So hold them in tmp.
@@ -669,8 +669,7 @@ void ExecutionContext::executeFunctions(ShutdownType type) {
       [](TypedValue v) {
         vm_call_user_func(VarNR{v}, init_null_variant,
                           RuntimeCoeffects::defaults());
-        // Implicit context should not have leaked between each call
-        assertx(!(*ImplicitContext::activeCtx));
+        assertx((*ImplicitContext::activeCtx) == (*ImplicitContext::inaccessibleCtx));
       }
     );
     tmp.append(funcs);
@@ -1430,12 +1429,12 @@ void ExecutionContext::requestInit() {
     SystemLib::mergePersistentUnits();
   }
 
-  assertx(!ImplicitContext::activeCtx.isInit());
-  ImplicitContext::activeCtx.initWith(nullptr);
-
   assertx(!ImplicitContext::inaccessibleCtx.isInit());
   ImplicitContext::inaccessibleCtx.initWith(initInaccessibleConext().detach());
 
+  assertx(!ImplicitContext::activeCtx.isInit());
+  ImplicitContext::activeCtx.initWith(*ImplicitContext::inaccessibleCtx);
+
   profileRequestStart();
 
   HHProf::Request::StartProfiling();

hphp/runtime/base/implicit-context.h

@@ -67,7 +67,7 @@ static Variant getBlameVectors();
 struct Saver {
   Saver() {
     m_context = *ImplicitContext::activeCtx;
-    *ImplicitContext::activeCtx = nullptr;
+    *ImplicitContext::activeCtx = *ImplicitContext::inaccessibleCtx;
   }
   ~Saver() {
     *ImplicitContext::activeCtx = m_context;

hphp/runtime/ext/hh/ext_implicit_context.php

@@ -187,7 +187,9 @@ enum class MemoizeOption: string {
   function backdoor<Tout>(
     (function()[defaults]: Tout) $fn
   )[/* 86backdoor */]: Tout {
-    $prev = \HH\ImplicitContext\_Private\set_implicit_context_by_value(null);
+    $prev = \HH\ImplicitContext\_Private\set_implicit_context_by_value(
+      \HH\ImplicitContext\_Private\get_inaccessible_implicit_context(),
+    );
     try {
       return $fn();
     } finally {
@@ -202,7 +204,9 @@ function backdoor<Tout>(
   async function backdoor_async<Tout>(
     (function()[defaults]: Awaitable<Tout>) $fn
   )[/* 86backdoor */]: Awaitable<Tout> {
-    $prev = \HH\ImplicitContext\_Private\set_implicit_context_by_value(null);
+    $prev = \HH\ImplicitContext\_Private\set_implicit_context_by_value(
+      \HH\ImplicitContext\_Private\get_inaccessible_implicit_context()
+    );
     try {
       $result = $fn();
     } finally {

hphp/test/server/http/multipart/error_page_clear_implicit_context.php

@@ -5,7 +5,11 @@
 <<__EntryPoint>>
 function main_error() :mixed{
   echo "Reading implicit context\n";
-  var_dump(IntContext::get());
+  try {
+    var_dump(IntContext::get());
+  } catch (InvalidOperationException $e){
+    echo $e->getMessage();
+  }
 }
 
 // FILE: main.php

hphp/test/server/http/tests/error_page_clear_implicit_context.php.expect

@@ -1,5 +1,5 @@
 Sandbox: 0 (sandbox0) Version: 0
 --------------------------------------------------------
 Reading implicit context
-NULL
+Implicit context is set to inaccessible
 --------------------------------------------------------

hphp/test/slow/implicit-context/async-basic-4.php

@@ -3,6 +3,9 @@
 <<__EntryPoint>>
 async function main() :Awaitable<mixed>{
   include 'async-implicit.inc';
-
-  var_dump(IntContext::getContext());
+  try {
+    var_dump(IntContext::getContext());
+  } catch (InvalidOperationException $e) {
+    echo $e->getMessage();
+  }
 }

hphp/test/slow/implicit-context/async-basic-4.php.expect

@@ -1 +1 @@
-NULL
+Implicit context is set to inaccessible

hphp/test/slow/implicit-context/basic-4.php

@@ -3,6 +3,9 @@
 <<__EntryPoint>>
 function main() :mixed{
   include 'implicit.inc';
-
-  var_dump(IntContext::getContext());
+  try {
+    var_dump(IntContext::getContext());
+  } catch (InvalidOperationException $e) {
+    echo $e->getMessage();
+  }
 }

hphp/test/slow/implicit-context/basic-4.php.expect

@@ -1 +1 @@
-NULL
+Implicit context is set to inaccessible

hphp/test/slow/implicit-context/coeffect-2.php

@@ -7,31 +7,35 @@ public static function set(int $context, (function (): int) $f)[zoned] :mixed{
     return parent::runWith($context, $f);
   }
   public static function getContext()[zoned]: ?int {
-    return parent::get();
+    try {
+      return parent::get();
+    } catch (InvalidOperationException $e) {
+      echo $e->getMessage() . "\n";;
+    }
   }
 }
 
 function g()[defaults] :mixed{
   $context = IntContext::getContext() ?? 'null';
-  echo "in g context is $context \n";
+  echo "in g context is $context\n";
 }
 
 function h_exception()[defaults] :mixed{
   $context = IntContext::getContext() ?? 'null';
-  echo "in h_exception context is $context \n";
+  echo "in h_exception context is $context\n";
   echo "throwing exception from h_exception()\n";
   throw new Exception();
 }
 
 function f()[zoned] :mixed{
   $context = IntContext::getContext() ?? 'null';
-  echo "in f context is $context \n";
+  echo "in f context is $context\n";
   HH\Coeffects\backdoor(g<>);
   $context = IntContext::getContext() ?? 'null';
-  echo "back in f context is $context \n";
+  echo "back in f context is $context\n";
   try { HH\Coeffects\backdoor(h_exception<>); } catch (Exception $_) {}
   $context = IntContext::getContext() ?? 'null';
-  echo "back in f context is $context \n";
+  echo "back in f context is $context\n";
 }
 
 <<__EntryPoint>>

hphp/test/slow/implicit-context/coeffect-2.php.expect

@@ -1,7 +1,9 @@
 Setting context to 5
-in f context is 5 
-in g context is null 
-back in f context is 5 
-in h_exception context is null 
+in f context is 5
+Implicit context is set to inaccessible
+in g context is null
+back in f context is 5
+Implicit context is set to inaccessible
+in h_exception context is null
 throwing exception from h_exception()
-back in f context is 5 
+back in f context is 5

hphp/test/slow/implicit-context/gc.php.expect

@@ -1,2 +1,4 @@
-NULL
+vec(1) {
+  string(14) "%Inaccessible%"
+}
 string(4) "done"

hphp/test/slow/implicit-context/get_state_unsafe.php

@@ -28,11 +28,11 @@ function mici(): void {
 
 <<__EntryPoint>>
 function main(): void {
-  expect(HH\ImplicitContext\State::NULL);
+  expect(HH\ImplicitContext\State::INACCESSIBLE);
   IntContext::set(
     0,
     () ==> expect(HH\ImplicitContext\State::VALUE),
   );
-  expect(HH\ImplicitContext\State::NULL);
+  expect(HH\ImplicitContext\State::INACCESSIBLE);
   mici();
 }

hphp/test/slow/implicit-context/keyed-1.php

@@ -3,7 +3,7 @@
 function dump_ctx_data() :mixed{
   try {
     echo ClassContext::getContext()->name() . "\n";
-  } catch (Exception $e) {
+  } catch (InvalidOperationException $e) {
     echo $e->getMessage() . "\n";
   }
 }

hphp/test/slow/implicit-context/keyed-1.php.expectf

@@ -1,17 +1,21 @@
 >>>>> from null
-  Before: Expected nonnull, got null
-Expected nonnull, got null
+  Before: Implicit context is set to inaccessible
+Implicit context is set to inaccessible
 Hash:
-NULL
+vec(1) {
+  string(14) "%%Inaccessible%%"
+}
 memoNoArg passed
-  After: Expected nonnull, got null
+  After: Implicit context is set to inaccessible
 ------------------------
-  Before: Expected nonnull, got null
-Expected nonnull, got null
+  Before: Implicit context is set to inaccessible
+Implicit context is set to inaccessible
 Hash:
-NULL
+vec(1) {
+  string(14) "%%Inaccessible%%"
+}
 memoWithArg passed
-  After: Expected nonnull, got null
+  After: Implicit context is set to inaccessible
 ------------------------
 >>>>> from value
   Before: C
@@ -36,20 +40,10 @@ memoWithArg passed
 ------------------------
 >>>>> from inaccessible
   Before: Implicit context is set to inaccessible
-Implicit context is set to inaccessible
-Hash:
-vec(1) {
-  string(14) "%%Inaccessible%%"
-}
 memoNoArg passed
   After: Implicit context is set to inaccessible
 ------------------------
   Before: Implicit context is set to inaccessible
-Implicit context is set to inaccessible
-Hash:
-vec(1) {
-  string(14) "%%Inaccessible%%"
-}
 memoWithArg passed
   After: Implicit context is set to inaccessible
 ------------------------
@@ -63,14 +57,14 @@ memoWithArg passed
   After: Implicit context is set to inaccessible
 ------------------------
 >>>>> from soft run with
-  Before: Expected nonnull, got null
+  Before: Implicit context is set to inaccessible
 memoNoArg passed
-  After: Expected nonnull, got null
+  After: Implicit context is set to inaccessible
 ------------------------
-  Before: Expected nonnull, got null
+  Before: Implicit context is set to inaccessible
 memoWithArg passed
-  After: Expected nonnull, got null
+  After: Implicit context is set to inaccessible
 ------------------------
 >>>>> final report
-No arg ran: 3 times
-With arg ran: 3 times
+No arg ran: 2 times
+With arg ran: 2 times

hphp/test/slow/implicit-context/keyed-2.php.expect

@@ -1,2 +1,2 @@
-No arg ran: 3 times
-With arg ran: 3 times
+No arg ran: 2 times
+With arg ran: 2 times

hphp/test/slow/implicit-context/memo-dynamic-1.php

@@ -36,17 +36,27 @@ function f(bool $has_ctx) :mixed{
     "memo_soft_ic_inaccessible",
   ];
   foreach ($v as $f) {
-    if ($has_ctx) {
-      echo "  Before: " . ClassContext::getContext()->name() . "\n";
+    try {
+      if ($has_ctx) {
+        echo "  Before: " . ClassContext::getContext()->name() . "\n";
+      }
+    } catch (InvalidOperationException $e) {
+      echo $f . " failed with: " . $e->getMessage() . "\n";
     }
+
     try {
       $f();
       echo $f . " passed\n";
     } catch (Exception $e) {
       echo $f . " failed with: " . $e->getMessage() . "\n";
     }
-    if ($has_ctx) {
-      echo "  After: " . ClassContext::getContext()->name() . "\n";
+
+    try {
+      if ($has_ctx) {
+        echo "  After: " . ClassContext::getContext()->name() . "\n";
+      }
+    } catch (InvalidOperationException $e) {
+      echo $f . " failed with: " . $e->getMessage() . "\n";
     }
     echo "------------------------\n";
   }

hphp/test/slow/implicit-context/memo-dynamic-1.php.expectf

@@ -30,6 +30,8 @@ memo_soft_ic_inaccessible passed
 ------------------------
 memo_normal passed
 ------------------------
+string(14) "%%Inaccessible%%"
+
 memo_keyed passed
 ------------------------
 memo_ic_inaccessible passed

hphp/test/slow/implicit-context/no-ic-contexts.php

@@ -3,24 +3,28 @@
 <<__Memoize>>
 function memo_with_leak_safe_zero_param()[leak_safe]: void {
   $hash = HH\ImplicitContext\_Private\get_implicit_context_debug_info() ?? 'NULL';
+  $hash = HH\Lib\Str\join($hash, ", ");
   echo "memo_with_leak_safe_zero_param hash: $hash\n";
 }
 
 <<__Memoize>>
 function memo_with_leak_safe_single_param($a)[leak_safe]: void {
   $hash = HH\ImplicitContext\_Private\get_implicit_context_debug_info() ?? 'NULL';
+  $hash = HH\Lib\Str\join($hash, ", ");
   echo "memo_with_leak_safe_single_param hash: $hash\n";
 }
 
 <<__Memoize>>
 function memo_with_pure_zero_param()[]: void {
   $hash = HH\ImplicitContext\_Private\get_implicit_context_debug_info() ?? 'NULL';
+  $hash = HH\Lib\Str\join($hash, ", ");
   echo "memo_with_pure_zero_param hash: $hash\n";
 }
 
 <<__Memoize>>
 function memo_with_pure_single_param($a)[]: void {
   $hash = HH\ImplicitContext\_Private\get_implicit_context_debug_info() ?? 'NULL';
+  $hash = HH\Lib\Str\join($hash, ", ");
   echo "memo_with_pure_single_param hash: $hash\n";
 }
 
@@ -52,6 +56,7 @@ function fn_with_leak_safe() [leak_safe]: void  {
 <<__Memoize>>
 function no_param_with_leaksafe_only()[leak_safe]: void {
   $hash = HH\ImplicitContext\_Private\get_implicit_context_debug_info() ?? 'NULL';
+  $hash = HH\Lib\Str\join($hash, ", ");
   echo "no_param_with_leaksafe_only hash: $hash";
   echo "\n";
 }

hphp/test/slow/implicit-context/no-ic-contexts.php.expect

@@ -1,10 +1,10 @@
 defaults memo_no_param hash: %Inaccessible%
 defaults memo_single_param hash: %Inaccessible%
-memo_with_leak_safe_zero_param hash: NULL
-memo_with_leak_safe_single_param hash: NULL
-memo_with_pure_zero_param hash: NULL
-memo_with_pure_single_param hash: NULL
-no_param_with_leaksafe_only hash: NULL
+memo_with_leak_safe_zero_param hash: %Inaccessible%
+memo_with_leak_safe_single_param hash: %Inaccessible%
+memo_with_pure_zero_param hash: %Inaccessible%
+memo_with_pure_single_param hash: %Inaccessible%
+no_param_with_leaksafe_only hash: %Inaccessible%
 no_param_with_leaksafe_and_defaults hash: %Inaccessible%
 no_param_with_leaksafe_local_only hash: %Inaccessible%
 no_param_with_leaksafe_shallow_only hash: %Inaccessible%