Georg Ostrovski
bb80b55ae1
The lazy init of log_config used a single atomic flag (env_checked) with a load-then-store pattern, allowing two threads to both enter the init path and concurrently write to the non-atomic log_config.topics field. Replace with a two-phase atomic init: an atomic exchange on env_init_claimed ensures exactly one thread enters the init, while env_init_done (with acquire/release semantics) signals completion and provides the happens-before edge that makes log_config writes visible to other threads. Also adds mj_atomic_exchange_bool to engine_crossplatform.h (both MSVC and GCC/Clang variants). PiperOrigin-RevId: 941202181 Change-Id: I59b6801c7b4b8b0e1647d82d2aeb534a90fb66fb
116 lines
3.4 KiB
C
116 lines
3.4 KiB
C
// Copyright 2021 DeepMind Technologies Limited
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef MUJOCO_SRC_ENGINE_ENGINE_CROSSPLATFORM_H_
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#define MUJOCO_SRC_ENGINE_ENGINE_CROSSPLATFORM_H_
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// IWYU pragma: begin_keep
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#if !defined(__cplusplus)
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#include <stddef.h>
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#include <stdlib.h>
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#else
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#include <cstddef>
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#include <cstdlib>
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#endif
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// IWYU pragma: end_keep
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// Case-insensitive comparison functions.
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#ifdef _WIN32
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#define strcasecmp _stricmp
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#define strncasecmp _strnicmp
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#else // assumes POSIX
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#include <strings.h>
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#endif
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// Environment variable handling.
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#ifdef _WIN32
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#define setenv(name, value, overwrite) _putenv_s(name, value)
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#define unsetenv(name) _putenv_s(name, "")
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#endif
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// Switch-case fallthrough annotation.
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#if defined(__cplusplus)
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#define mjFALLTHROUGH [[fallthrough]]
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#elif defined(__clang__) || (defined(__GNUC__) && __GNUC__ >= 7)
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#define mjFALLTHROUGH __attribute__((fallthrough))
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#else
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#define mjFALLTHROUGH ((void) 0)
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#endif
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// MSVC only provides max_align_t in C++.
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#if defined(_MSC_VER) && !defined(__clang__) && !defined(__cplusplus)
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typedef long double mjtMaxAlign;
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#else
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typedef max_align_t mjtMaxAlign;
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#endif
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// Branch prediction hints.
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#if defined(__GNUC__)
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#define mjLIKELY(x) __builtin_expect(!!(x), 1)
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#define mjUNLIKELY(x) __builtin_expect(!!(x), 0)
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#else
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#define mjLIKELY(x) (x)
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#define mjUNLIKELY(x) (x)
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#endif
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// Define ADDRESS_SANITIZER if implied by other macros.
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#if !defined(ADDRESS_SANITIZER)
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#if defined(__SANITIZE_ADDRESS__)
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#define ADDRESS_SANITIZER
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#elif defined(__has_feature)
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#if __has_feature(address_sanitizer)
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#define ADDRESS_SANITIZER
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#endif
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#endif
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#endif
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// Atomics helper for size_t.
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#if defined(_MSC_VER) && !defined(__clang__)
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#include <intrin.h>
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#define mj_atomic_add_size_t(ptr, val) \
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(size_t)_InterlockedExchangeAdd64((__int64 volatile*)(ptr), (__int64)(val))
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#else
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#define mj_atomic_add_size_t(ptr, val) \
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__atomic_fetch_add(ptr, val, __ATOMIC_RELAXED)
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#endif
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// Atomics helpers for mjtBool (1-byte _Bool) with acquire/release semantics.
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#if defined(_MSC_VER) && !defined(__clang__)
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#define mj_atomic_load_bool(ptr) \
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(mjtBool) _InterlockedCompareExchange8((volatile char*)(ptr), 0, 0)
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#define mj_atomic_store_bool(ptr, val) \
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(void)_InterlockedExchange8((volatile char*)(ptr), (char)(val))
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#define mj_atomic_exchange_bool(ptr, val) \
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(mjtBool) _InterlockedExchange8((volatile char*)(ptr), (char)(val))
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#else
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#define mj_atomic_load_bool(ptr) __atomic_load_n(ptr, __ATOMIC_ACQUIRE)
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#define mj_atomic_store_bool(ptr, val) __atomic_store_n(ptr, val, __ATOMIC_RELEASE)
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#define mj_atomic_exchange_bool(ptr, val) __atomic_exchange_n(ptr, val, __ATOMIC_ACQ_REL)
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifdef ADDRESS_SANITIZER
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int mj__comparePcFuncName(void* pc1, void* pc2);
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const char* mj__getPcDebugInfo(void* pc);
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#endif
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#ifdef __cplusplus
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} // extern "C"
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#endif
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#endif // MUJOCO_SRC_ENGINE_ENGINE_CROSSPLATFORM_H_
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