protected internal override async Task ReleaseLeaseAsync(string id, string leaseId)
{
try
{
var partitionKey = new PartitionKey(id);
// Reads the document with the lease
// If the lease is expired, try to update the document
var readResponse = await this.container.ReadItemAsync <CosmosDBLease>(id, partitionKey);
if (readResponse.StatusCode == HttpStatusCode.OK && readResponse.Resource.LeaseID == leaseId)
{
var newLease = new CosmosDBLease()
{
ID = id,
LeaseID = null,
LeasedUntil = null,
};
var replaceItemResponse = await this.container.ReplaceItemAsync <CosmosDBLease>(newLease, id, partitionKey, new ItemRequestOptions()
{
IfMatchEtag = readResponse.ETag,
});
}
}
catch (Exception)
{
throw;
}
}
private async Task <bool> TryCreateLeaseAsync(string id, string leaseId, TimeSpan throttleTime)
{
// Document did not exist. Try to be the first to created it, adquiring the lease
var newLease = new CosmosDBLease()
{
ID = id,
LeaseID = leaseId,
LeasedUntil = DateTime.UtcNow.Add(throttleTime),
};
try
{
var createResponse = await this.container.CreateItemAsync <CosmosDBLease>(
newLease,
new PartitionKey(id));
if (createResponse.StatusCode == HttpStatusCode.Created)
{
return(true);
}
}
catch (CosmosException ex) when(ex.StatusCode == HttpStatusCode.Conflict)
{
// document was created before, we did not get the lease
// do not throw exception
}
return(false);
}
/// <summary>
/// Tries to acquire a lease
/// </summary>
/// <param name="id"></param>
/// <param name="throttleTime"></param>
/// <param name="leaseId"></param>
/// <returns></returns>
protected internal override async Task <bool> TryAcquireLeaseAsync(string id, TimeSpan throttleTime, string leaseId)
{
var partitionKey = new PartitionKey(id);
// Document is already there, check if it has an expired lease
ItemResponse <CosmosDBLease> readResponse;
try
{
readResponse = await this.container.ReadItemAsync <CosmosDBLease>(id, partitionKey);
}
catch (CosmosException ex) when(ex.StatusCode == HttpStatusCode.NotFound)
{
// Does not exist: create it!
return(await TryCreateLeaseAsync(id, leaseId, throttleTime));
}
var existingLease = readResponse.Resource;
if (existingLease.LeasedUntil != null && existingLease.LeasedUntil.Value >= DateTime.UtcNow)
{
return(false);
}
var updatedLease = new CosmosDBLease()
{
ID = id,
LeaseID = leaseId,
LeasedUntil = DateTime.UtcNow.Add(throttleTime),
};
try
{
var updateLeaseResponse = await this.container.ReplaceItemAsync <CosmosDBLease>(
updatedLease,
id,
partitionKey,
new ItemRequestOptions()
{
IfMatchEtag = readResponse.ETag,
});
return(updateLeaseResponse.StatusCode == HttpStatusCode.OK);
}
catch (CosmosException ex) when(ex.StatusCode == HttpStatusCode.Conflict)
{
// someone else leased before us
return(false);
}
}