C# ICloudBlob.FetchAttributesAsync方法代码示例

 public static void WaitForCopyTask(ICloudBlob blob)
 {
     bool copyInProgress = true;
     while (copyInProgress)
     {
         Thread.Sleep(1000);
         blob.FetchAttributesAsync().Wait();
         copyInProgress = (blob.CopyState.Status == CopyStatus.Pending);
     }
 }

 public static async Task WaitForCopyAsync(ICloudBlob blob)
 {
     bool copyInProgress = true;
     while (copyInProgress)
     {
         await Task.Delay(1000);
         await blob.FetchAttributesAsync();
         copyInProgress = (blob.CopyState.Status == CopyStatus.Pending);
     }
 }

 /// <summary>
 /// Return a task that asynchronously fetch blob attributes
 /// </summary>
 /// <param name="blob">ICloud blob object</param>
 /// <param name="accessCondition">Access condition</param>
 /// <param name="options">Blob request options</param>
 /// <param name="operationContext">Operation context</param>
 /// <param name="cmdletCancellationToken">Cancellation token</param>
 /// <returns>Return a task that asynchronously fetch blob attributes</returns>
 public Task FetchBlobAttributesAsync(ICloudBlob blob, AccessCondition accessCondition, BlobRequestOptions options, OperationContext operationContext, CancellationToken cancellationToken)
 {
     return blob.FetchAttributesAsync(accessCondition, options, operationContext, cancellationToken);
 }

        /// <summary>
        /// Verifies the behavior of a lease while the lease holds. Once the lease expires, this method confirms that write operations succeed.
        /// The test is cut short once the <c>testLength</c> time has elapsed. (This last feature is necessary for infinite leases.)
        /// </summary>
        /// <param name="leasedBlob">The blob to test.</param>
        /// <param name="duration">The duration of the lease.</param>
        /// <param name="testLength">The maximum length of time to run the test.</param>
        /// <param name="tolerance">The allowed lease time error.</param>
        internal async Task BlobAcquireRenewLeaseTestAsync(ICloudBlob leasedBlob, TimeSpan? duration, TimeSpan testLength, TimeSpan tolerance)
        {
            OperationContext operationContext = new OperationContext();
            DateTime beginTime = DateTime.UtcNow;

            bool testOver = false;
            do
            {
                try
                {
                    // Attempt to write to the blob with no lease ID.
                    await leasedBlob.SetMetadataAsync(null, null, operationContext);

                    // The write succeeded, which means that the lease must have expired.

                    // If the lease was infinite then there is an error because it should not have expired.
                    Assert.IsNotNull(duration, "An infinite lease should not expire.");

                    // The lease should be past its expiration time.
                    Assert.IsTrue(DateTime.UtcNow - beginTime > duration - tolerance, "Writes should not succeed while lease is present.");

                    // Since the lease has expired, the test is over.
                    testOver = true;
                }
                catch
                {
                    if (operationContext.LastResult.ExtendedErrorInformation.ErrorCode == BlobErrorCodeStrings.LeaseIdMissing)
                    {
                        // We got this error because the lease has not expired yet.

                        // Make sure the lease is not past its expiration time yet.
                        DateTime currentTime = DateTime.UtcNow;
                        if (duration.HasValue)
                        {
                            Assert.IsTrue(currentTime - beginTime < duration + tolerance, "Writes should succeed after a lease expires.");
                        }

                        // End the test early if necessary.
                        if (currentTime - beginTime > testLength)
                        {
                            // The lease has not expired, but we're not waiting any longer.
                            return;
                        }
                    }
                    else
                    {
                        // Some other error occurred. Rethrow the exception.
                        throw;
                    }
                }

                // Attempt to read from the blob. This should always succeed.
                await leasedBlob.FetchAttributesAsync();

                // Wait 1 second before trying again.
                if (!testOver)
                {
                    await Task.Delay(TimeSpan.FromSeconds(1));
                }
            }
            while (!testOver);

            // The lease expired. Write to and read from the blob once more.
            await leasedBlob.SetMetadataAsync();
            await leasedBlob.FetchAttributesAsync();
        }

        /// <summary>
        /// Checks the lease status of a blob, both from its attributes and from a blob listing.
        /// </summary>
        /// <param name="blob">The blob to test.</param>
        /// <param name="expectedStatus">The expected lease status.</param>
        /// <param name="expectedState">The expected lease state.</param>
        /// <param name="expectedDuration">The expected lease duration.</param>
        /// <param name="description">A description of the circumstances that lead to the expected status.</param>
        private async Task CheckLeaseStatusAsync(
            ICloudBlob blob,
            LeaseStatus expectedStatus,
            LeaseState expectedState,
            LeaseDuration expectedDuration,
            string description)
        {
            await blob.FetchAttributesAsync();
            Assert.AreEqual(expectedStatus, blob.Properties.LeaseStatus, "LeaseStatus mismatch: " + description + " (from FetchAttributes)");
            Assert.AreEqual(expectedState, blob.Properties.LeaseState, "LeaseState mismatch: " + description + " (from FetchAttributes)");
            Assert.AreEqual(expectedDuration, blob.Properties.LeaseDuration, "LeaseDuration mismatch: " + description + " (from FetchAttributes)");

            BlobResultSegment blobs = await blob.Container.ListBlobsSegmentedAsync(blob.Name, true, BlobListingDetails.None, null, null, null, null);
            BlobProperties propertiesInListing = (from ICloudBlob b in blobs.Results
                                                  where b.Name == blob.Name
                                                  select b.Properties).Single();

            Assert.AreEqual(expectedStatus, propertiesInListing.LeaseStatus, "LeaseStatus mismatch: " + description + " (from ListBlobs)");
            Assert.AreEqual(expectedState, propertiesInListing.LeaseState, "LeaseState mismatch: " + description + " (from ListBlobs)");
            Assert.AreEqual(expectedDuration, propertiesInListing.LeaseDuration, "LeaseDuration mismatch: " + description + " (from ListBlobs)");
        }

 public static async Task CreateEmptyBlob(ICloudBlob blob)
 {
     var emptyByteArray = new byte[] { };
     await blob.UploadFromByteArrayAsync(emptyByteArray, 0, emptyByteArray.Length);
     await blob.FetchAttributesAsync();
 }