Composite locks

[moeen]

This pull request introduces new composite lock methods for various lock types via code generation.

Auto Generated Codes

• src/DistributedLock.Core/DistributedLockProviderExtensions.cs
• src/DistributedLock.Core/DistributedReaderWriterLockProviderExtensions.cs
• src/DistributedLock.Core/DistributedSemaphoreProviderExtensions.cs
• src/DistributedLock.Core/DistributedUpgradeableReaderWriterLockProviderExtensions.cs

[madelson]

Thanks for the contribution @moeen ! This is off to a great start!

[madelson]

Given that this method is fundamentally internal, does it need default values for these parameters? If not let's remove

[madelson]

While this flow works, I found it to be a bit hard to follow since you need to keep in mind that the handle constructor does a defensive copy of the list which makes clear ok and that the fact that we always dispose in the finally is made ok by the clear().

Let's make this small change which I think makes the intent clearer:

IDistributedSynchronizationHandle? handle = null;
try {
    foreach (var name in name)
    {
        var handle = ...
        if (handle is null) { break; }
        handles.Add(handle);
        ...
    }
}
finally {
    if (handle is null) { await DisposeAsyncHandles(handles).ConfigureAwait(false); }
}

return handle;

Let's do the same for the sync codepath

[madelson]

remove extra blank line

[madelson]

Let's make this a struct

[madelson]

Let's take in TimeoutValue since this will automatically validate for us that the TimeSpan is a valid timeout value. This is important because invalid values like -2 will otherwise get converted into valid values by Remaining.

[madelson]

This is a bug: if remaining becomes negative then it will become an invalid timeout or even Timeout.InfiniteTimespan!

Should be:

Remaining =>
    this._stopwatch is { Elapsed: var elapsed }
        ? elapsed >= timeout
            ? TimeSpan.Zero
            : timeout - elapsed
       : Timeout.InfiniteTimespan;

[madelson]

I love the use of """ strings here, but let's indent less:

var providerInterfaceCode = $$"""
    ...
    """;

Please address throughout.

[madelson]

Let's go ahead and add unit tests for all of these new methods in DistributedLockProviderExtensionsTest.

In particular:

• Let's cover all input validation/edge-case handling
• Let's cover the case where you go to acquire A, B with timeout 0 and B is already acquired -> you should get back null and A should be left in an unacquired state
• Let's test the "remaining time" logic. Might be easiest to test through mocking.