bkietz commented on code in PR #37040:
URL: https://github.com/apache/arrow/pull/37040#discussion_r1287279624
##########
cpp/src/arrow/device.h:
##########
@@ -105,6 +107,63 @@ class ARROW_EXPORT Device : public
std::enable_shared_from_this<Device>,
bool is_cpu_;
};
+/// \brief EXPERIMENTAL: An object that provides event/stream sync primitives
+///
+///
+class ARROW_EXPORT DeviceSync {
+ public:
+ explicit DeviceSync(void* sync_event) : sync_event_{sync_event},
owns_event_{false} {}
+ virtual ~DeviceSync() = default;
Review Comment:
The compiler-generated default constructor won't call release_event; I think
this destructor should probably do that
```suggestion
virtual ~DeviceSync() {
if (owns_event_) {
release_event(sync_event_);
}
}
```
##########
cpp/src/arrow/device.h:
##########
@@ -105,6 +107,63 @@ class ARROW_EXPORT Device : public
std::enable_shared_from_this<Device>,
bool is_cpu_;
};
+/// \brief EXPERIMENTAL: An object that provides event/stream sync primitives
+///
+///
+class ARROW_EXPORT DeviceSync {
+ public:
+ explicit DeviceSync(void* sync_event) : sync_event_{sync_event},
owns_event_{false} {}
+ virtual ~DeviceSync() = default;
+
+ /// @brief Block until sync event is completed.
+ ///
+ /// Should be a no-op for CPU devices.
+ virtual Status wait() = 0;
+
+ /// @brief Make the provided stream wait on the sync event.
+ ///
+ /// Tells the provided stream that it should wait until the
+ /// synchronization event is completed without blocking the CPU.
+ /// @param stream Should be appropriate for the underlying device
+ virtual Status stream_wait(void* stream) = 0;
+
+ virtual void set_stream(void* stream) { stream_ = stream; }
+
+ Result<void*> get_event() {
+ if (!sync_event_) {
+ ARROW_ASSIGN_OR_RAISE(sync_event_, create_event());
+ owns_event_ = true;
+ }
+ return sync_event_;
+ }
+
+ void clear_event() {
Review Comment:
Would this be used (instead of just destroying the DeviceSync)? I think it'd
be best to keep the interface minimal until we can document the usage which
each function anticipates
##########
cpp/src/arrow/device.h:
##########
@@ -165,6 +224,8 @@ class ARROW_EXPORT MemoryManager : public
std::enable_shared_from_this<MemoryMan
static Result<std::shared_ptr<Buffer>> ViewBuffer(
const std::shared_ptr<Buffer>& source, const
std::shared_ptr<MemoryManager>& to);
+ virtual Result<std::shared_ptr<DeviceSync>> MakeDeviceSync(void* sync_event
= nullptr);
Review Comment:
Nit: don't put default arguments on virtual functions. Also, if possible:
for virtual functions which aren't pure virtual, make the default impl obvious
by inlining
```suggestion
virtual Result<std::shared_ptr<DeviceSync>> MakeDeviceSync() {
return nullptr;
}
Result<std::shared_ptr<DeviceSync>> MakeDeviceSync(void *sync_event);
```
##########
cpp/src/arrow/device.h:
##########
@@ -105,6 +107,63 @@ class ARROW_EXPORT Device : public
std::enable_shared_from_this<Device>,
bool is_cpu_;
};
+/// \brief EXPERIMENTAL: An object that provides event/stream sync primitives
+///
+///
+class ARROW_EXPORT DeviceSync {
+ public:
+ explicit DeviceSync(void* sync_event) : sync_event_{sync_event},
owns_event_{false} {}
Review Comment:
This constructor should probably be protected; IIUC we'll always be
constructing a device-specific derived class and never a bare DeviceSync
##########
cpp/src/arrow/device.h:
##########
@@ -105,6 +107,63 @@ class ARROW_EXPORT Device : public
std::enable_shared_from_this<Device>,
bool is_cpu_;
};
+/// \brief EXPERIMENTAL: An object that provides event/stream sync primitives
+///
+///
+class ARROW_EXPORT DeviceSync {
+ public:
+ explicit DeviceSync(void* sync_event) : sync_event_{sync_event},
owns_event_{false} {}
+ virtual ~DeviceSync() = default;
+
+ /// @brief Block until sync event is completed.
+ ///
+ /// Should be a no-op for CPU devices.
+ virtual Status wait() = 0;
+
+ /// @brief Make the provided stream wait on the sync event.
+ ///
+ /// Tells the provided stream that it should wait until the
+ /// synchronization event is completed without blocking the CPU.
+ /// @param stream Should be appropriate for the underlying device
+ virtual Status stream_wait(void* stream) = 0;
Review Comment:
Similarly: it's not clear when this would be used instead of set_stream()
then wait()
##########
cpp/src/arrow/c/bridge.cc:
##########
@@ -1362,7 +1362,7 @@ namespace {
// The ArrowArray is released on destruction.
struct ImportedArrayData {
struct ArrowArray array_;
- void* sync_event_;
+ std::shared_ptr<DeviceSync> device_sync;
Review Comment:
```suggestion
std::shared_ptr<DeviceSync> device_sync_;
```
##########
cpp/src/arrow/c/bridge.cc:
##########
@@ -739,19 +738,20 @@ Status ExportDeviceArray(const Array& array, RawSyncEvent
sync_event,
exporter.Finish(&out->array);
auto* pdata =
reinterpret_cast<ExportedArrayPrivateData*>(out->array.private_data);
- pdata->sync_event_ = sync_event;
- out->sync_event = sync_event.sync_event;
+ pdata->sync_ = sync;
Review Comment:
... then move into `pdata`
```suggestion
pdata->sync_ = std::move(sync);
```
##########
cpp/src/arrow/buffer.h:
##########
@@ -346,6 +346,8 @@ class ARROW_EXPORT Buffer {
static Result<std::shared_ptr<Buffer>> ViewOrCopy(
std::shared_ptr<Buffer> source, const std::shared_ptr<MemoryManager>&
to);
+ virtual std::shared_ptr<DeviceSync> get_device_sync() { return nullptr; }
Review Comment:
My vote for the bikeshed is:
```
// nest the class inside Device
DeviceSync -> Device::SyncEvent
// for trivial property accessors we don't usually prefix `get_`
get_device_sync -> device_sync_event
(or) -> GetDeviceSyncEvent
```
##########
cpp/src/arrow/c/bridge.cc:
##########
@@ -714,11 +713,11 @@ Result<std::pair<std::optional<DeviceAllocationType>,
int64_t>> ValidateDeviceIn
return std::make_pair(device_type, device_id);
}
-Status ExportDeviceArray(const Array& array, RawSyncEvent sync_event,
+Status ExportDeviceArray(const Array& array, std::shared_ptr<DeviceSync>& sync,
Review Comment:
Agreed, please take this argument by value
```suggestion
Status ExportDeviceArray(const Array& array, std::shared_ptr<DeviceSync>
sync,
```
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