Bug 1785046 - Part 4: Use async move on printing to file on Windows. r=nika,emilio

Differential Revision: https://phabricator.services.mozilla.com/D163509

widget/nsIDeviceContextSpec.cpp

@@ -6,8 +6,14 @@
 #include "nsIDeviceContextSpec.h"
 
 #include "gfxPoint.h"
+#include "mozilla/gfx/PrintPromise.h"
+#include "nsError.h"
 #include "nsIPrintSettings.h"
 
+#include "mozilla/Components.h"
+#include "mozilla/TaskQueue.h"
+
+using mozilla::MakeRefPtr;
 using mozilla::gfx::PrintEndDocumentPromise;
 
 // We have some platform specific code here rather than in the appropriate
@@ -58,3 +64,24 @@ nsIDeviceContextSpec::EndDocumentPromiseFromResult(nsresult aResult,
              ? PrintEndDocumentPromise::CreateAndResolve(true, aSite)
              : PrintEndDocumentPromise::CreateAndReject(aResult, aSite);
 }
+
+RefPtr<PrintEndDocumentPromise> nsIDeviceContextSpec::EndDocumentAsync(
+    const char* aCallSite, AsyncEndDocumentFunction aFunction) {
+  auto promise =
+      MakeRefPtr<PrintEndDocumentPromise::Private>("PrintEndDocumentPromise");
+
+  NS_DispatchBackgroundTask(
+      NS_NewRunnableFunction(
+          "EndDocumentAsync",
+          [promise, function = std::move(aFunction)]() mutable {
+            const auto result = function();
+            if (NS_SUCCEEDED(result)) {
+              promise->Resolve(true, __func__);
+            } else {
+              promise->Reject(result, __func__);
+            }
+          }),
+      NS_DISPATCH_EVENT_MAY_BLOCK);
+
+  return promise;
+}

widget/nsIDeviceContextSpec.h

@@ -10,6 +10,7 @@
 #include "nsISupports.h"
 #include "mozilla/StaticPrefs_print.h"
 #include "mozilla/gfx/PrintPromise.h"
+#include "mozilla/MoveOnlyFunction.h"
 
 class nsIWidget;
 class nsIPrintSettings;
@@ -82,6 +83,10 @@ class nsIDeviceContextSpec : public nsISupports {
   NS_IMETHOD EndPage() = 0;
 
  protected:
+  using AsyncEndDocumentFunction = mozilla::MoveOnlyFunction<nsresult()>;
+  static RefPtr<mozilla::gfx::PrintEndDocumentPromise> EndDocumentAsync(
+      const char* aCallSite, AsyncEndDocumentFunction aFunction);
+
   static RefPtr<mozilla::gfx::PrintEndDocumentPromise>
   EndDocumentPromiseFromResult(nsresult aResult, const char* aSite);
 

widget/windows/nsDeviceContextSpecWin.cpp

@@ -333,20 +333,15 @@ already_AddRefed<PrintTarget> nsDeviceContextSpecWin::MakePrintTarget() {
 }
 
 RefPtr<PrintEndDocumentPromise> nsDeviceContextSpecWin::EndDocument() {
-  return nsIDeviceContextSpec::EndDocumentPromiseFromResult(DoEndDocument(),
-                                                            __func__);
-}
-
-nsresult nsDeviceContextSpecWin::DoEndDocument() {
   if (mPrintSettings->GetOutputDestination() !=
           nsIPrintSettings::kOutputDestinationFile ||
       mOutputFormat != nsIPrintSettings::kOutputFormatPDF) {
-    return NS_OK;
+    return PrintEndDocumentPromise::CreateAndResolve(true, __func__);
   }
 
 #ifdef MOZ_ENABLE_SKIA_PDF
   if (mPrintViaSkPDF) {
-    return NS_OK;
+    return PrintEndDocumentPromise::CreateAndResolve(true, __func__);
   }
 #endif
 
@@ -356,25 +351,32 @@ nsresult nsDeviceContextSpecWin::DoEndDocument() {
   mPrintSettings->GetToFileName(targetPath);
 
   if (targetPath.IsEmpty()) {
-    return NS_OK;
+    return PrintEndDocumentPromise::CreateAndResolve(true, __func__);
   }
 
   // We still need to move the file to its actual destination.
   nsCOMPtr<nsIFile> destFile;
-  MOZ_TRY(NS_NewLocalFile(targetPath, false, getter_AddRefs(destFile)));
+  auto rv = NS_NewLocalFile(targetPath, false, getter_AddRefs(destFile));
+  if (NS_FAILED(rv)) {
+    return PrintEndDocumentPromise::CreateAndReject(rv, __func__);
+  }
+
+  return nsIDeviceContextSpec::EndDocumentAsync(
+      __func__,
+      [destFile = std::move(destFile),
+       tempFile = std::move(mTempFile)]() -> nsresult {
         nsAutoString destLeafName;
         MOZ_TRY(destFile->GetLeafName(destLeafName));
 
         nsCOMPtr<nsIFile> destDir;
         MOZ_TRY(destFile->GetParent(getter_AddRefs(destDir)));
 
-  // This should be fine - Windows API calls usually prevent moving between
-  // different volumes (See Win32 API's `MOVEFILE_COPY_ALLOWED` flag), but we
-  // handle that down this call.
-  MOZ_TRY(mTempFile->MoveTo(destDir, destLeafName));
-  mTempFile = nullptr;
-
+        // This should be fine - Windows API calls usually prevent moving
+        // between different volumes (See Win32 API's `MOVEFILE_COPY_ALLOWED`
+        // flag), but we handle that down this call.
+        MOZ_TRY(tempFile->MoveTo(destDir, destLeafName));
         return NS_OK;
+      });
 }
 
 //----------------------------------------------------------------------------------

widget/windows/nsDeviceContextSpecWin.h

@@ -69,9 +69,6 @@ class nsDeviceContextSpecWin : public nsIDeviceContextSpec {
   // A temporary file to create an "anonymous" print target. See bug 1664253,
   // this should ideally not be needed.
   nsCOMPtr<nsIFile> mTempFile;
-
- private:
-  nsresult DoEndDocument();
 };
 
 //-------------------------------------------------------------------------