public async Task <long> SSRedisTransactionIncrAsync()
{
long last = default;
_ssredis.Del(Key); // todo: asyncify
await using var trans = await _ssAsync.CreateTransactionAsync();
for (int i = 0; i < PER_TEST; i++)
{
trans.QueueCommand(r => r.IncrementValueAsync(Key), l => last = l);
}
await trans.CommitAsync();
return(last);
}
async ValueTask <bool> IDistributedLockAsync.UnlockAsync(string key, long lockExpire, IRedisClientAsync client, CancellationToken token)
{
if (lockExpire <= 0)
{
return(false);
}
long lockVal = 0;
var nativeClient = (IRedisNativeClientAsync)client;
var pipe = client.CreatePipeline();
await using (pipe.ConfigureAwait(false))
{
pipe.QueueCommand(r => ((IRedisNativeClientAsync)r).WatchAsync(new[] { key }, token));
pipe.QueueCommand(r => ((IRedisNativeClientAsync)r).GetAsync(key, token),
x => lockVal = (x != null) ? BitConverter.ToInt64(x, 0) : 0);
await pipe.FlushAsync(token).ConfigureAwait(false);
}
if (lockVal != lockExpire)
{
if (lockVal != 0)
{
Debug.WriteLine($"Unlock(): Failed to unlock key {key}; lock has been acquired by another client ");
}
else
{
Debug.WriteLine($"Unlock(): Failed to unlock key {key}; lock has been identifed as a zombie and harvested ");
}
await nativeClient.UnWatchAsync(token).ConfigureAwait(false);
return(false);
}
var trans = await client.CreateTransactionAsync(token).ConfigureAwait(false);
await using (trans.ConfigureAwait(false))
{
trans.QueueCommand(r => ((IRedisNativeClientAsync)r).DelAsync(key, token));
var rc = await trans.CommitAsync(token).ConfigureAwait(false);
if (!rc)
{
Debug.WriteLine($"Unlock(): Failed to delete key {key}; lock has been acquired by another client ");
}
return(rc);
}
}
async ValueTask <LockState> IDistributedLockAsync.LockAsync(string key, int acquisitionTimeout, int lockTimeout, IRedisClientAsync client, CancellationToken token)
{
long lockExpire = 0;
// cannot lock on a null key
if (key == null)
{
return(new LockState(LOCK_NOT_ACQUIRED, lockExpire));
}
const int sleepIfLockSet = 200;
acquisitionTimeout *= 1000; //convert to ms
int tryCount = (acquisitionTimeout / sleepIfLockSet) + 1;
var ts = (DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0));
var newLockExpire = CalculateLockExpire(ts, lockTimeout);
var nativeClient = (IRedisNativeClientAsync)client;
long wasSet = await nativeClient.SetNXAsync(key, BitConverter.GetBytes(newLockExpire), token).ConfigureAwait(false);
int totalTime = 0;
while (wasSet == LOCK_NOT_ACQUIRED && totalTime < acquisitionTimeout)
{
int count = 0;
while (wasSet == 0 && count < tryCount && totalTime < acquisitionTimeout)
{
await Task.Delay(sleepIfLockSet).ConfigureAwait(false);
totalTime += sleepIfLockSet;
ts = (DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0));
newLockExpire = CalculateLockExpire(ts, lockTimeout);
wasSet = await nativeClient.SetNXAsync(key, BitConverter.GetBytes(newLockExpire), token).ConfigureAwait(false);
count++;
}
// acquired lock!
if (wasSet != LOCK_NOT_ACQUIRED)
{
break;
}
// handle possibliity of crashed client still holding the lock
var pipe = client.CreatePipeline();
await using (pipe.ConfigureAwait(false))
{
long lockValue = 0;
pipe.QueueCommand(r => ((IRedisNativeClientAsync)r).WatchAsync(new[] { key }, token));
pipe.QueueCommand(r => ((IRedisNativeClientAsync)r).GetAsync(key, token), x => lockValue = (x != null) ? BitConverter.ToInt64(x, 0) : 0);
await pipe.FlushAsync(token).ConfigureAwait(false);
// if lock value is 0 (key is empty), or expired, then we can try to acquire it
ts = (DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0));
if (lockValue < ts.TotalSeconds)
{
ts = (DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0));
newLockExpire = CalculateLockExpire(ts, lockTimeout);
var trans = await client.CreateTransactionAsync(token).ConfigureAwait(false);
await using (trans.ConfigureAwait(false))
{
var expire = newLockExpire;
trans.QueueCommand(r => ((IRedisNativeClientAsync)r).SetAsync(key, BitConverter.GetBytes(expire), token: token));
if (await trans.CommitAsync(token).ConfigureAwait(false))
{
wasSet = LOCK_RECOVERED; //recovered lock!
}
}
}
else
{
await nativeClient.UnWatchAsync(token).ConfigureAwait(false);
}
}
if (wasSet != LOCK_NOT_ACQUIRED)
{
break;
}
await Task.Delay(sleepIfLockSet).ConfigureAwait(false);
totalTime += sleepIfLockSet;
}
if (wasSet != LOCK_NOT_ACQUIRED)
{
lockExpire = newLockExpire;
}
return(new LockState(wasSet, lockExpire));
}
