feat: Add SetLength API

src/Momento.Sdk/CacheClient.cs

@@ -3,7 +3,6 @@
 using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
-using Google.Protobuf.WellKnownTypes;
 using Microsoft.Extensions.Logging;
 using Momento.Sdk.Auth;
 using Momento.Sdk.Config;
@@ -900,6 +899,22 @@ public async Task<CacheSetFetchResponse> SetFetchAsync(string cacheName, string
 
         return await this.DataClient.SetFetchAsync(cacheName, setName);
     }
+
+    /// <inheritdoc />
+    public async Task<CacheSetLengthResponse> SetLengthAsync(string cacheName, string setName)
+    {
+        try
+        {
+            Utils.ArgumentNotNull(cacheName, nameof(cacheName));
+            Utils.ArgumentNotNull(setName, nameof(setName));
+        }
+        catch (ArgumentNullException e)
+        {
+            return new CacheSetLengthResponse.Error(new InvalidArgumentException(e.Message));
+        }
+
+        return await this.DataClient.SetLengthAsync(cacheName, setName);
+    }
 
     /// <inheritdoc />
     public async Task<CacheListConcatenateFrontResponse> ListConcatenateFrontAsync(string cacheName, string listName, IEnumerable<byte[]> values, int? truncateBackToSize = null, CollectionTtl ttl = default(CollectionTtl))

src/Momento.Sdk/ICacheClient.cs

@@ -530,6 +530,16 @@ public interface ICacheClient : IDisposable
     /// <param name="setName">The set to fetch.</param>
     /// <returns>Task representing with the status of the fetch operation and the associated set.</returns>
     public Task<CacheSetFetchResponse> SetFetchAsync(string cacheName, string setName);
+
+    /// <summary>
+    /// Calculate the length of a set in the cache.
+    ///
+    /// A set that does not exist is interpreted to have length 0.
+    /// </summary>
+    /// <param name="cacheName">Name of the cache to perform the lookup in.</param>
+    /// <param name="setName">The dictionary to calculate length.</param>
+    /// <returns>Task representing the length of the dictionary.</returns>
+    public Task<CacheSetLengthResponse> SetLengthAsync(string cacheName, string setName);
 
     /// <summary>
     /// Push multiple values to the beginning of a list.

src/Momento.Sdk/Internal/DataGrpcManager.cs

@@ -39,6 +39,7 @@ public interface IDataClient
     public Task<_SetUnionResponse> SetUnionAsync(_SetUnionRequest request, CallOptions callOptions);
     public Task<_SetDifferenceResponse> SetDifferenceAsync(_SetDifferenceRequest request, CallOptions callOptions);
     public Task<_SetFetchResponse> SetFetchAsync(_SetFetchRequest request, CallOptions callOptions);
+    public Task<_SetLengthResponse> SetLengthAsync(_SetLengthRequest request, CallOptions callOptions);
     public Task<_ListPushFrontResponse> ListPushFrontAsync(_ListPushFrontRequest request, CallOptions callOptions);
     public Task<_ListPushBackResponse> ListPushBackAsync(_ListPushBackRequest request, CallOptions callOptions);
     public Task<_ListPopFrontResponse> ListPopFrontAsync(_ListPopFrontRequest request, CallOptions callOptions);
@@ -166,6 +167,12 @@ public async Task<_SetFetchResponse> SetFetchAsync(_SetFetchRequest request, Cal
         var wrapped = await _middlewares.WrapRequest(request, callOptions, (r, o) => _generatedClient.SetFetchAsync(r, o));
         return await wrapped.ResponseAsync;
     }
+
+    public async Task<_SetLengthResponse> SetLengthAsync(_SetLengthRequest request, CallOptions callOptions)
+    {
+        var wrapped = await _middlewares.WrapRequest(request, callOptions, (r, o) => _generatedClient.SetLengthAsync(r, o));
+        return await wrapped.ResponseAsync;
+    }
 
     public async Task<_ListPushFrontResponse> ListPushFrontAsync(_ListPushFrontRequest request, CallOptions callOptions)
     {

src/Momento.Sdk/Internal/ScsDataClient.cs

@@ -307,6 +307,11 @@ public async Task<CacheSetFetchResponse> SetFetchAsync(string cacheName, string
     {
         return await SendSetFetchAsync(cacheName, setName);
     }
+
+    public async Task<CacheSetLengthResponse> SetLengthAsync(string cacheName, string setName)
+    {
+        return await SendSetLengthAsync(cacheName, setName);
+    }
 
     public async Task<CacheListConcatenateFrontResponse> ListConcatenateFrontAsync(string cacheName, string listName, IEnumerable<byte[]> values, int? truncateBackToSize = null, CollectionTtl ttl = default(CollectionTtl))
     {
@@ -934,6 +939,31 @@ private async Task<CacheSetFetchResponse> SendSetFetchAsync(string cacheName, st
 
         return this._logger.LogTraceCollectionRequestSuccess(REQUEST_TYPE_SET_FETCH, cacheName, setName, new CacheSetFetchResponse.Miss());
     }
+
+    const string REQUEST_TYPE_SET_LENGTH = "SET_LENGTH";
+    private async Task<CacheSetLengthResponse> SendSetLengthAsync(string cacheName, string setName)
+    {
+        _SetLengthRequest request = new() { SetName = setName.ToByteString() };
+        _SetLengthResponse response;
+        var metadata = MetadataWithCache(cacheName);
+
+        try
+        {
+            this._logger.LogTraceExecutingCollectionRequest(REQUEST_TYPE_SET_LENGTH, cacheName, setName);
+            response = await this.grpcManager.Client.SetLengthAsync(request, new CallOptions(headers: MetadataWithCache(cacheName), deadline: CalculateDeadline()));
+        }
+        catch (Exception e)
+        {
+            return this._logger.LogTraceCollectionRequestError(REQUEST_TYPE_SET_LENGTH, cacheName, setName, new CacheSetLengthResponse.Error(_exceptionMapper.Convert(e, metadata)));
+        }
+
+        if (response.SetCase == _SetLengthResponse.SetOneofCase.Missing)
+        {
+            return this._logger.LogTraceCollectionRequestSuccess(REQUEST_TYPE_SET_LENGTH, cacheName, setName, new CacheSetLengthResponse.Miss());
+        }
+
+        return this._logger.LogTraceCollectionRequestSuccess(REQUEST_TYPE_SET_LENGTH, cacheName, setName, new CacheSetLengthResponse.Hit(response));
+    }
 
     const string REQUEST_TYPE_LIST_CONCATENATE_FRONT = "LIST_CONCATENATE_FRONT";
 

src/Momento.Sdk/Responses/CacheSetLengthResponse.cs

@@ -0,0 +1,105 @@
+using Momento.Protos.CacheClient;
+using Momento.Sdk.Exceptions;
+
+namespace Momento.Sdk.Responses;
+
+/// <summary>
+/// Parent response type for a cache set length request. The
+/// response object is resolved to a type-safe object of one of
+/// the following subtypes:
+/// <list type="bullet">
+/// <item><description>CacheSetLengthResponse.Hit</description></item>
+/// <item><description>CacheSetLengthResponse.Miss</description></item>
+/// <item><description>CacheSetLengthResponse.Error</description></item>
+/// </list>
+/// Pattern matching can be used to operate on the appropriate subtype.
+/// For example:
+/// <code>
+/// if (response is CacheSetLengthResponse.Hit hitResponse)
+/// {
+///     return hitResponse.Length;
+/// }
+/// else if (response is CacheSetLengthResponse.Miss missResponse)
+/// {
+///     // handle missResponse as appropriate
+/// }
+/// else if (response is CacheSetLengthResponse.Error errorResponse)
+/// {
+///     // handle error as appropriate
+/// }
+/// else
+/// {
+///     // handle unexpected response
+/// }
+/// </code>
+/// </summary>
+public abstract class CacheSetLengthResponse
+{
+    /// <include file="../docs.xml" path='docs/class[@name="Hit"]/description/*' />
+    public class Hit : CacheSetLengthResponse
+    {
+        /// <summary>
+        /// The length of the set. If the set is missing or empty, the result is zero.
+        /// </summary>
+        public int Length { get; private set; } = 0;
+
+        /// <summary>
+        ///
+        /// </summary>
+        /// <param name="response">The cache response.</param>
+        public Hit(_SetLengthResponse response)
+        {
+            if(response.SetCase == _SetLengthResponse.SetOneofCase.Found) {
+                Length = checked((int)response.Found.Length);
+            }
+        }
+
+        /// <inheritdoc />
+        public override string ToString()
+        {
+            return $"{base.ToString()}: Length: {Length}";
+        }
+    }
+
+    /// <include file="../docs.xml" path='docs/class[@name="Miss"]/description/*' />
+    public class Miss : CacheSetLengthResponse
+    {
+
+    }
+
+    /// <include file="../docs.xml" path='docs/class[@name="Error"]/description/*' />
+    public class Error : CacheSetLengthResponse, IError
+    {
+        private readonly SdkException _error;
+
+        /// <include file="../docs.xml" path='docs/class[@name="Error"]/constructor/*' />
+        public Error(SdkException error)
+        {
+            _error = error;
+        }
+
+        /// <inheritdoc />
+        public SdkException InnerException
+        {
+            get => _error;
+        }
+
+        /// <inheritdoc />
+        public MomentoErrorCode ErrorCode
+        {
+            get => _error.ErrorCode;
+        }
+
+        /// <inheritdoc />
+        public string Message
+        {
+            get => $"{_error.MessageWrapper}: {_error.Message}";
+        }
+
+        /// <inheritdoc />
+        public override string ToString()
+        {
+            return $"{base.ToString()}: {this.Message}";
+        }
+    }
+}

tests/Integration/Momento.Sdk.Tests/SetTest.cs

@@ -608,4 +608,26 @@ public async Task SetDeleteAsync_SetExists_HappyPath()
         Assert.True(deleteResponse is CacheDeleteResponse.Success, $"Unexpected response: {deleteResponse}");
         Assert.True(await client.SetFetchAsync(cacheName, setName) is CacheSetFetchResponse.Miss);
     }
+
+    [Fact]
+    public async Task SetLengthAsync_SetIsMissing()
+    {
+        var setName = Utils.NewGuidString();
+        CacheSetLengthResponse response = await client.SetLengthAsync(cacheName, setName);
+        Assert.True(response is CacheSetLengthResponse.Miss, $"Unexpected response: {response}");
+    }
+
+    [Fact]
+    public async Task SetLengthAsync_HappyPath()
+    {
+        var setName = Utils.NewGuidString();
+        var element = Utils.NewGuidByteArray();
+
+        await client.SetAddElementAsync(cacheName, setName, element);
+
+        CacheSetLengthResponse lengthResponse = await client.SetLengthAsync(cacheName, setName);
+        Assert.True(lengthResponse is CacheSetLengthResponse.Hit, $"Unexpected response: {lengthResponse}");
+        var hitResponse = (CacheSetLengthResponse.Hit)lengthResponse;
+        Assert.Equal(1, hitResponse.Length);
+    }
 }