dotnet-sdk/examples/Client/DistributedLock/Controllers/BindingController.cs

using System;
using System.Linq;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;
using Dapr;
using Dapr.Client;
using DistributedLock.Model;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;

namespace DistributedLock.Controllers
{
    [ApiController]
    public class BindingController : ControllerBase
    {
        private DaprClient client;
        private ILogger<BindingController> logger;
        private string appId;

        public BindingController(DaprClient client, ILogger<BindingController> logger)
        {
            this.client = client;
            this.logger = logger;
            this.appId = Environment.GetEnvironmentVariable("APP_ID");
        }

        [HttpPost("cronbinding")]
        [Obsolete]
        public async Task<IActionResult> HandleBindingEvent()
        {
            logger.LogInformation($"Received binding event on {appId}, scanning for work.");

            var request = new BindingRequest("localstorage", "list");
            var result = client.InvokeBindingAsync(request);

            var rawData = result.Result.Data.ToArray();
            var files = JsonSerializer.Deserialize<string[]>(rawData);

            if (files != null)
            {
                foreach (var file in files.Select(file => file.Split("/").Last()).OrderBy(file => file))
                {
                    await AttemptToProcessFile(file);
                }
            }
            
            return Ok();
        }


        [Obsolete]
        private async Task AttemptToProcessFile(string fileName)
        {
            // Locks are Disposable and will automatically unlock at the end of a 'using' statement.
            logger.LogInformation($"Attempting to lock: {fileName}");
            await using (var fileLock = await client.Lock("redislock", fileName, appId, 60))
            {
                if (fileLock.Success)
                {
                    logger.LogInformation($"Successfully locked file: {fileName}");

                    // Get the file after we've locked it, we're safe here because of the lock.
                    var fileState = await GetFile(fileName);

                    if (fileState == null)
                    {
                        logger.LogWarning($"File {fileName} has already been processed!");
                        return;
                    }

                    // "Analyze" the file before committing it to our remote storage.
                    fileState.Analysis = fileState.Number > 50 ? "High" : "Low";

                    // Save it to remote storage.
                    await client.SaveStateAsync("redisstore", fileName, fileState);

                    // Remove it from local storage.
                    var bindingDeleteRequest = new BindingRequest("localstorage", "delete");
                    bindingDeleteRequest.Metadata["fileName"] = fileName;
                    await client.InvokeBindingAsync(bindingDeleteRequest);

                    logger.LogInformation($"Done processing {fileName}");
                }
                else
                {
                    logger.LogWarning($"Failed to lock {fileName}.");
                }
            }
        }

        private async Task<StateData> GetFile(string fileName)
        {
            try
            {
                var bindingGetRequest = new BindingRequest("localstorage", "get");
                bindingGetRequest.Metadata["fileName"] = fileName;

                var bindingResponse = await client.InvokeBindingAsync(bindingGetRequest);
                return JsonSerializer.Deserialize<StateData>(bindingResponse.Data.ToArray());
            }
            catch (DaprException)
            {
                return null;
            }            
        }
    }
}