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Merge pull request #81 from saltosystems/feature/reuse-syscall-callba…
…cks-to-avoid-reaching-the-Golang-limit codegen/delegates: reuse callbacks to avoid reaching go limits
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,139 @@ | ||
| //go:build windows | ||
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| package delegate | ||
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| import ( | ||
| "sync" | ||
| "syscall" | ||
| "unsafe" | ||
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| "github.com/go-ole/go-ole" | ||
| ) | ||
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| // Only a limited number of callbacks may be created in a single Go process, | ||
| // and any memory allocated for these callbacks is never released. | ||
| // Between NewCallback and NewCallbackCDecl, at least 1024 callbacks can always be created. | ||
| var ( | ||
| queryInterfaceCallback = syscall.NewCallback(queryInterface) | ||
| addRefCallback = syscall.NewCallback(addRef) | ||
| releaseCallback = syscall.NewCallback(release) | ||
| invokeCallback = syscall.NewCallback(invoke) | ||
| ) | ||
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| // Delegate represents a WinRT delegate class. | ||
| type Delegate interface { | ||
| GetIID() *ole.GUID | ||
| Invoke(instancePtr, rawArgs0, rawArgs1, rawArgs2, rawArgs3, rawArgs4, rawArgs5, rawArgs6, rawArgs7, rawArgs8 unsafe.Pointer) uintptr | ||
| AddRef() uint64 | ||
| Release() uint64 | ||
| } | ||
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| // Callbacks contains the syscalls registered on Windows. | ||
| type Callbacks struct { | ||
| QueryInterface uintptr | ||
| AddRef uintptr | ||
| Release uintptr | ||
| Invoke uintptr | ||
| } | ||
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| var mutex = sync.RWMutex{} | ||
| var instances = make(map[uintptr]Delegate) | ||
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| // RegisterCallbacks adds the given pointer and the Delegate it points to to our instances. | ||
| // This is required to redirect received callbacks to the correct object instance. | ||
| // The function returns the callbacks to use when creating a new delegate instance. | ||
| func RegisterCallbacks(ptr unsafe.Pointer, inst Delegate) *Callbacks { | ||
| mutex.Lock() | ||
| defer mutex.Unlock() | ||
| instances[uintptr(ptr)] = inst | ||
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| return &Callbacks{ | ||
| QueryInterface: queryInterfaceCallback, | ||
| AddRef: addRefCallback, | ||
| Release: releaseCallback, | ||
| Invoke: invokeCallback, | ||
| } | ||
| } | ||
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| func getInstance(ptr unsafe.Pointer) (Delegate, bool) { | ||
| mutex.RLock() // locks writing, allows concurrent read | ||
| defer mutex.RUnlock() | ||
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| i, ok := instances[uintptr(ptr)] | ||
| return i, ok | ||
| } | ||
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| func removeInstance(ptr unsafe.Pointer) { | ||
| mutex.Lock() | ||
| defer mutex.Unlock() | ||
| delete(instances, uintptr(ptr)) | ||
| } | ||
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| func queryInterface(instancePtr unsafe.Pointer, iidPtr unsafe.Pointer, ppvObject *unsafe.Pointer) uintptr { | ||
| instance, ok := getInstance(instancePtr) | ||
| if !ok { | ||
| // instance not found | ||
| return ole.E_POINTER | ||
| } | ||
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| // Checkout these sources for more information about the QueryInterface method. | ||
| // - https://docs.microsoft.com/en-us/cpp/atl/queryinterface | ||
| // - https://docs.microsoft.com/en-us/windows/win32/api/unknwn/nf-unknwn-iunknown-queryinterface(refiid_void) | ||
|
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| if ppvObject == nil { | ||
| // If ppvObject (the address) is nullptr, then this method returns E_POINTER. | ||
| return ole.E_POINTER | ||
| } | ||
|
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| // This function must adhere to the QueryInterface defined here: | ||
| // https://docs.microsoft.com/en-us/windows/win32/api/unknwn/nn-unknwn-iunknown | ||
| if iid := (*ole.GUID)(iidPtr); ole.IsEqualGUID(iid, instance.GetIID()) || ole.IsEqualGUID(iid, ole.IID_IUnknown) || ole.IsEqualGUID(iid, ole.IID_IInspectable) { | ||
| *ppvObject = instancePtr | ||
| } else { | ||
| *ppvObject = nil | ||
| // Return E_NOINTERFACE if the interface is not supported | ||
| return ole.E_NOINTERFACE | ||
| } | ||
|
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| // If the COM object implements the interface, then it returns | ||
| // a pointer to that interface after calling IUnknown::AddRef on it. | ||
| (*ole.IUnknown)(*ppvObject).AddRef() | ||
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| // Return S_OK if the interface is supported | ||
| return ole.S_OK | ||
| } | ||
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| func invoke(instancePtr, rawArgs0, rawArgs1, rawArgs2, rawArgs3, rawArgs4, rawArgs5, rawArgs6, rawArgs7, rawArgs8 unsafe.Pointer) uintptr { | ||
| instance, ok := getInstance(instancePtr) | ||
| if !ok { | ||
| // instance not found | ||
| return ole.E_FAIL | ||
| } | ||
|
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| return instance.Invoke(instancePtr, rawArgs0, rawArgs1, rawArgs2, rawArgs3, rawArgs4, rawArgs5, rawArgs6, rawArgs7, rawArgs8) | ||
| } | ||
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| func addRef(instancePtr unsafe.Pointer) uint64 { | ||
| instance, ok := getInstance(instancePtr) | ||
| if !ok { | ||
| // instance not found | ||
| return ole.E_FAIL | ||
| } | ||
|
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| return instance.AddRef() | ||
| } | ||
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| func release(instancePtr unsafe.Pointer) uint64 { | ||
| instance, ok := getInstance(instancePtr) | ||
| if !ok { | ||
| // instance not found | ||
| return ole.E_FAIL | ||
| } | ||
|
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| rem := instance.Release() | ||
| if rem == 0 { | ||
| // remove this delegate | ||
| removeInstance(instancePtr) | ||
| } | ||
| return rem | ||
| } |
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