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Introduce new safe atomic types.

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The idea behind this is to avoid subtle bugs that are a result of
accidentally not using atomic operations to reference variables that
must always be used atomically.

This commit does not convert every atomic variable to the new system,
however going forward this will need to be adopted over time.
This commit is contained in:
David Reid
2022-11-13 12:05:32 +10:00
parent 4f7f00d76a
commit 84e911726c
1 changed files with 138 additions and 6 deletions
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miniaudio.h
+138 -6
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@@ -3748,6 +3748,10 @@ typedef ma_uint32 ma_bool32;
#define MA_TRUE 1
#define MA_FALSE 0
/* These float types are not used universally by miniaudio. It's to simplify some macro expansion for atomic types. */
typedef float ma_float;
typedef double ma_double;
typedef void* ma_handle;
typedef void* ma_ptr;
typedef void (* ma_proc)(void);
@@ -4195,6 +4199,64 @@ typedef struct
} ma_lcg;
/*
Atomics.
These are typesafe structures to prevent errors as a result of forgetting to reference variables atomically. It's too
easy to introduce subtle bugs where you accidentally do a regular assignment instead of an atomic load/store, etc. By
using a struct we can enforce the use of atomics at compile time.
These types are declared in the header section because we need to reference them in structs below, but functions for
using them are only exposed in the implementation section. I do not want these to be part of the public API.
There's a few downsides to this system. The first is that you need to declare a new struct for each type. Below are
some macros to help with the declarations. They will be named like so:
ma_atomic_uint32 - atomic ma_uint32
ma_atomic_int32 - atomic ma_int32
ma_atomic_uint64 - atomic ma_uint64
ma_atomic_float - atomic float
ma_atomic_bool32 - atomic ma_bool32
The other downside is that atomic pointers are extremely messy. You need to declare a new struct for each specific
type of pointer you need to make atomic. For example, an atomic ma_node* will look like this:
MA_ATOMIC_SAFE_TYPE_IMPL_PTR(node)
Which will declare a type struct that's named like so:
ma_atomic_ptr_node
Functions to use the atomic types are declared in the implementation section. All atomic functions are prefixed with
the name of the struct. For example:
ma_atomic_uint32_set() - Atomic store of ma_uint32
ma_atomic_uint32_get() - Atomic load of ma_uint32
etc.
For pointer types it's the same, which makes them a bit messy to use due to the length of each function name, but in
return you get type safety and enforcement of atomic operations.
*/
#define MA_ATOMIC_SAFE_TYPE_DECL(c89TypeExtension, typeSize, type) \
typedef struct \
{ \
MA_ATOMIC(typeSize, ma_##type) value; \
} ma_atomic_##type; \
#define MA_ATOMIC_SAFE_TYPE_DECL_PTR(type) \
typedef struct \
{ \
MA_ATOMIC(MA_SIZEOF_PTR, ma_##type*) value; \
} ma_atomic_ptr_##type; \
MA_ATOMIC_SAFE_TYPE_DECL(32, 4, uint32)
MA_ATOMIC_SAFE_TYPE_DECL(i32, 4, int32)
MA_ATOMIC_SAFE_TYPE_DECL(64, 8, uint64)
MA_ATOMIC_SAFE_TYPE_DECL(f32, 4, float)
MA_ATOMIC_SAFE_TYPE_DECL(32, 4, bool32)
/* Spinlocks are 32-bit for compatibility reasons. */
typedef ma_uint32 ma_spinlock;
@@ -10118,7 +10180,7 @@ struct ma_resource_manager_data_buffer
ma_bool32 seekToCursorOnNextRead; /* On the next read we need to seek to the frame cursor. */
MA_ATOMIC(4, ma_result) result; /* Keeps track of a result of decoding. Set to MA_BUSY while the buffer is still loading. Set to MA_SUCCESS when loading is finished successfully. Otherwise set to some other code. */
MA_ATOMIC(4, ma_bool32) isLooping; /* Can be read and written by different threads at the same time. Must be used atomically. */
ma_bool32 isConnectorInitialized; /* Used for asynchronous loading to ensure we don't try to initialize the connector multiple times while waiting for the node to fully load. */
ma_atomic_bool32 isConnectorInitialized; /* Used for asynchronous loading to ensure we don't try to initialize the connector multiple times while waiting for the node to fully load. */
union
{
ma_decoder decoder; /* Supply type is ma_resource_manager_data_supply_type_encoded */
@@ -15449,6 +15511,76 @@ static C89ATOMIC_INLINE void c89atomic_spinlock_unlock(volatile c89atomic_spinlo
#endif
/* c89atomic.h end */
#define MA_ATOMIC_SAFE_TYPE_IMPL(c89TypeExtension, type) \
static MA_INLINE ma_##type ma_atomic_##type##_get(ma_atomic_##type* x) \
{ \
return c89atomic_load_##c89TypeExtension(&x->value); \
} \
static MA_INLINE void ma_atomic_##type##_set(ma_atomic_##type* x, ma_##type value) \
{ \
c89atomic_store_##c89TypeExtension(&x->value, value); \
} \
static MA_INLINE ma_##type ma_atomic_##type##_exchange(ma_atomic_##type* x, ma_##type value) \
{ \
return c89atomic_exchange_##c89TypeExtension(&x->value, value); \
} \
static MA_INLINE ma_bool32 ma_atomic_##type##_compare_exchange(ma_atomic_##type* x, ma_##type* expected, ma_##type desired) \
{ \
return c89atomic_compare_exchange_weak_##c89TypeExtension(&x->value, expected, desired); \
} \
static MA_INLINE ma_##type ma_atomic_##type##_fetch_add(ma_atomic_##type* x, ma_##type y) \
{ \
return c89atomic_fetch_add_##c89TypeExtension(&x->value, y); \
} \
static MA_INLINE ma_##type ma_atomic_##type##_fetch_sub(ma_atomic_##type* x, ma_##type y) \
{ \
return c89atomic_fetch_sub_##c89TypeExtension(&x->value, y); \
} \
static MA_INLINE ma_##type ma_atomic_##type##_fetch_or(ma_atomic_##type* x, ma_##type y) \
{ \
return c89atomic_fetch_or_##c89TypeExtension(&x->value, y); \
} \
static MA_INLINE ma_##type ma_atomic_##type##_fetch_xor(ma_atomic_##type* x, ma_##type y) \
{ \
return c89atomic_fetch_xor_##c89TypeExtension(&x->value, y); \
} \
static MA_INLINE ma_##type ma_atomic_##type##_fetch_and(ma_atomic_##type* x, ma_##type y) \
{ \
return c89atomic_fetch_and_##c89TypeExtension(&x->value, y); \
} \
static MA_INLINE ma_##type ma_atomic_##type##_compare_and_swap(ma_atomic_##type* x, ma_##type expected, ma_##type desired) \
{ \
return c89atomic_compare_and_swap_##c89TypeExtension(&x->value, expected, desired); \
} \
#define MA_ATOMIC_SAFE_TYPE_IMPL_PTR(type) \
static MA_INLINE ma_##type* ma_atomic_ptr_##type##_get(ma_atomic_ptr_##type* x) \
{ \
return c89atomic_load_ptr((void**)&x->value); \
} \
static MA_INLINE void ma_atomic_ptr_##type##_set(ma_atomic_ptr_##type* x, ma_##type* value) \
{ \
c89atomic_store_ptr((void**)&x->value, (void*)value); \
} \
static MA_INLINE ma_##type* ma_atomic_ptr_##type##_exchange(ma_atomic_ptr_##type* x, ma_##type* value) \
{ \
return c89atomic_exchange_ptr((void**)&x->value, (void*)value); \
} \
static MA_INLINE ma_bool32 ma_atomic_ptr_##type##_compare_exchange(ma_atomic_ptr_##type* x, ma_##type** expected, ma_##type* desired) \
{ \
return c89atomic_compare_exchange_weak_ptr((void**)&x->value, (void*)expected, (void*)desired); \
} \
static MA_INLINE ma_##type* ma_atomic_ptr_##type##_compare_and_swap(ma_atomic_ptr_##type* x, ma_##type* expected, ma_##type* desired) \
{ \
return (ma_##type*)c89atomic_compare_and_swap_ptr((void**)&x->value, (void*)expected, (void*)desired); \
} \
MA_ATOMIC_SAFE_TYPE_IMPL(32, uint32)
MA_ATOMIC_SAFE_TYPE_IMPL(i32, int32)
MA_ATOMIC_SAFE_TYPE_IMPL(64, uint64)
MA_ATOMIC_SAFE_TYPE_IMPL(f32, float)
MA_ATOMIC_SAFE_TYPE_IMPL(32, bool32)
MA_API ma_uint64 ma_calculate_frame_count_after_resampling(ma_uint32 sampleRateOut, ma_uint32 sampleRateIn, ma_uint64 frameCountIn)
@@ -65761,7 +65893,7 @@ static ma_result ma_resource_manager__init_decoder(ma_resource_manager* pResourc
static ma_bool32 ma_resource_manager_data_buffer_has_connector(ma_resource_manager_data_buffer* pDataBuffer)
{
return pDataBuffer->isConnectorInitialized; /* TODO: Need to make this atomic. */
return ma_atomic_bool32_get(&pDataBuffer->isConnectorInitialized);
}
static ma_data_source* ma_resource_manager_data_buffer_get_connector(ma_resource_manager_data_buffer* pDataBuffer)
@@ -65791,7 +65923,7 @@ static ma_result ma_resource_manager_data_buffer_init_connector(ma_resource_mana
MA_ASSERT(pDataBuffer != NULL);
MA_ASSERT(pConfig != NULL);
MA_ASSERT(pDataBuffer->isConnectorInitialized == MA_FALSE);
MA_ASSERT(ma_resource_manager_data_buffer_has_connector(pDataBuffer) == MA_FALSE);
/* The underlying data buffer must be initialized before we'll be able to know how to initialize the backend. */
result = ma_resource_manager_data_buffer_node_result(pDataBuffer->pNode);
@@ -65848,7 +65980,7 @@ static ma_result ma_resource_manager_data_buffer_init_connector(ma_resource_mana
ma_data_source_set_loop_point_in_pcm_frames(pDataBuffer, pConfig->loopPointBegInPCMFrames, pConfig->loopPointEndInPCMFrames);
ma_data_source_set_looping(pDataBuffer, pConfig->isLooping);
pDataBuffer->isConnectorInitialized = MA_TRUE;
ma_atomic_bool32_set(&pDataBuffer->isConnectorInitialized, MA_TRUE);
if (pInitNotification != NULL) {
ma_async_notification_signal(pInitNotification);
@@ -68509,7 +68641,7 @@ static ma_result ma_job_process__resource_manager__load_data_buffer(ma_job* pJob
}
/* Try initializing the connector if we haven't already. */
isConnectorInitialized = pDataBuffer->isConnectorInitialized;
isConnectorInitialized = ma_resource_manager_data_buffer_has_connector(pDataBuffer);
if (isConnectorInitialized == MA_FALSE) {
dataSupplyType = ma_resource_manager_data_buffer_node_get_data_supply_type(pDataBuffer->pNode);
@@ -68565,7 +68697,7 @@ done:
If at this point the data buffer has not had it's connector initialized, it means the
notification event was never signalled which means we need to signal it here.
*/
if (pDataBuffer->isConnectorInitialized == MA_FALSE && result != MA_SUCCESS) {
if (ma_resource_manager_data_buffer_has_connector(pDataBuffer) == MA_FALSE && result != MA_SUCCESS) {
if (pJob->data.resourceManager.loadDataBuffer.pInitNotification != NULL) {
ma_async_notification_signal(pJob->data.resourceManager.loadDataBuffer.pInitNotification);
}