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HarelMHarelM
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Add lazy cache for memory mapped file and keep files in the cache for 30 minutes.
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‎ElevationWebApi.sln.DotSettings.user‎

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<wpf:ResourceDictionary xml:space="preserve" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:ss="urn:shemas-jetbrains-com:settings-storage-xaml" xmlns:wpf="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
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<s:String x:Key="/Default/CodeInspection/ExcludedFiles/FilesAndFoldersToSkip2/=7020124F_002D9FFC_002D4AC3_002D8F3D_002DAAB8E0240759_002Ff_003AArgumentSpecificationsFactory_002Ecs_002Fl_003A_002E_002E_003F_002E_002E_003FLibrary_003FApplication_0020Support_003FJetBrains_003FRider2024_002E3_003Fresharper_002Dhost_003FDecompilerCache_003Fdecompiler_003F402b2077f38742cb9b381ab9e79e493229c00_003F4c_003Fc2df050d_003FArgumentSpecificationsFactory_002Ecs/@EntryIndexedValue">ForceIncluded</s:String>
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‎ElevationWebApiTests/MemoryMapElevationProviderTests.cs‎

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using NSubstitute;
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using Microsoft.Extensions.Logging;
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using System.Runtime.CompilerServices;
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using LazyCache;
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namespace ElevationWebApiTests;
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@@ -24,7 +25,7 @@ public void Initialize()
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var hosting = Substitute.For<IWebHostEnvironment>();
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hosting.ContentRootFileProvider = new PhysicalFileProvider( GetSourceFileDirectory()!);
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var logger = Substitute.For<ILogger<MemoryMapElevationProvider>>();
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provider = new MemoryMapElevationProvider(hosting, logger);
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provider = new MemoryMapElevationProvider(hosting, logger, new CachingService());
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}
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‎README.md‎

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@@ -21,3 +21,8 @@ You can choose between two types of elevation providers by specifying the `ELEVA
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`MMAP` - For memory mapped elevation provider
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Default - In memory elevation provider
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The memory mapped elevation provider is using a cache to store the files.
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You can change the cache sliding window timeout using `CACHE_SLIDING_WINDOW` environment variable.
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The default is 30 and the units are minutes.
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This means that if a file is not used in the last 30 minutes it will be evacuated from the cache.
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‎src/ElevationWebApi.csproj‎

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</PropertyGroup>
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<ItemGroup>
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<PackageReference Include="LazyCache.AspNetCore" Version="2.4.0" />
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<PackageReference Include="NetTopologySuite" Version="2.5.0" />
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<PackageReference Include="SharpZipLib" Version="1.3.3" />
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<PackageReference Include="Swashbuckle.AspNetCore" Version="6.5.0" />

‎src/MemoryMapElevationProvider.cs‎

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using System;
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using System.Collections.Concurrent;
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using System.IO;
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using System.IO.MemoryMappedFiles;
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using System.Linq;
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using System.Threading.Tasks;
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using LazyCache;
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using Microsoft.AspNetCore.Hosting;
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using Microsoft.Extensions.Caching.Memory;
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using Microsoft.Extensions.FileProviders;
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using Microsoft.Extensions.Logging;
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using NetTopologySuite.Geometries;
@@ -20,18 +21,22 @@ public class MemoryMapElevationProvider : IElevationProvider
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{
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private readonly ILogger<MemoryMapElevationProvider> _logger;
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private readonly IFileProvider _fileProvider;
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private readonly ConcurrentDictionary<Coordinate, Task<FileAndSamples>> _mappedFilesCache;
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private readonly IAppCache _appCache;
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private readonly int _cacheSlidingWindowTimeInMinutes;
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/// <summary>
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/// Constructor
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/// </summary>
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/// <param name="webHostEnvironment"></param>
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/// <param name="logger"></param>
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public MemoryMapElevationProvider(IWebHostEnvironment webHostEnvironment, ILogger<MemoryMapElevationProvider> logger)
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/// <param name="appCache"></param>
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public MemoryMapElevationProvider(IWebHostEnvironment webHostEnvironment, ILogger<MemoryMapElevationProvider> logger, IAppCache appCache)
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{
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_logger = logger;
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_appCache = appCache;
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_fileProvider = webHostEnvironment.ContentRootFileProvider;
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_mappedFilesCache = new();
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var cacheSlidingWindow = Environment.GetEnvironmentVariable("CACHE_SLIDING_WINDOW");
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_cacheSlidingWindowTimeInMinutes = string.IsNullOrWhiteSpace(cacheSlidingWindow) ? 30 : int.Parse(cacheSlidingWindow);
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}
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/// <summary>
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var tasks = latLngs.Select(async latLng =>
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{
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var key = new Coordinate(Math.Floor(latLng[0]), Math.Floor(latLng[1]));
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if (!_mappedFilesCache.ContainsKey(key))
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var info = await _appCache.GetOrAddAsync(key.ToString(), () =>
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{
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var filePath = Path.Join(ElevationHelper.ELEVATION_CACHE, ElevationHelper.KeyToFileName(key));
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var fileInfo = _fileProvider.GetFileInfo(filePath);
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if (!fileInfo.Exists)
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return Task.Run(() =>
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{
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return 0;
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}
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_logger.LogInformation($"Loading {fileInfo.PhysicalPath} into memory mapped cache");
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_mappedFilesCache[key] = Task.Run(() => new FileAndSamples(MemoryMappedFile.CreateFromFile(fileInfo.PhysicalPath!, FileMode.Open), ElevationHelper.SamplesFromLength(fileInfo.Length)));
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}
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var info = await _mappedFilesCache[key];
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var filePath = Path.Join(ElevationHelper.ELEVATION_CACHE, ElevationHelper.KeyToFileName(key));
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var fileInfo = _fileProvider.GetFileInfo(filePath);
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if (!fileInfo.Exists)
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{
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_logger.LogWarning($"Missing hgt file for {key}");
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return new FileAndSamples(null, 0);
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}
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_logger.LogInformation($"Loading {fileInfo.PhysicalPath} into memory mapped cache");
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return new FileAndSamples(
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MemoryMappedFile.CreateFromFile(fileInfo.PhysicalPath!, FileMode.Open),
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ElevationHelper.SamplesFromLength(fileInfo.Length));
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});
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}, TimeSpan.FromMinutes(_cacheSlidingWindowTimeInMinutes));
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if (info.File == null)
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{
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return 0;
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}
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var exactLocation = new Coordinate(Math.Abs(latLng[0] - key.X) * (info.Samples - 1),
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(1 - Math.Abs(latLng[1] - key.Y)) * (info.Samples - 1));
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‎src/Startup.cs‎

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/// <param name="services"></param>
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public void ConfigureServices(IServiceCollection services)
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{
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services.AddLazyCache();
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if (Environment.GetEnvironmentVariable("ELEVATION_PROVIDER") == "MMAP")
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{
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services.AddSingleton<IElevationProvider, MemoryMapElevationProvider>();

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