Broke out SQL calls in DatabaseServerMessenger and BatchedDatabaseServerMessenger into a service and repository layer.

src/Umbraco.Infrastructure/Persistence/Repositories/Implement/CacheInstructionRepository.cs

@@ -0,0 +1,73 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using NPoco;
+using Umbraco.Cms.Core.Models;
+using Umbraco.Cms.Core.Persistence.Repositories;
+using Umbraco.Cms.Core.Scoping;
+using Umbraco.Cms.Infrastructure.Persistence.Dtos;
+using Umbraco.Cms.Infrastructure.Persistence.Factories;
+using Umbraco.Extensions;
+
+namespace Umbraco.Cms.Infrastructure.Persistence.Repositories.Implement
+{
+    /// <summary>
+    /// Represents the NPoco implementation of <see cref="ICacheInstructionRepository"/>.
+    /// </summary>
+    internal class CacheInstructionRepository : ICacheInstructionRepository
+    {
+        private readonly IScopeAccessor _scopeAccessor;
+
+        public CacheInstructionRepository(IScopeAccessor scopeAccessor) => _scopeAccessor = scopeAccessor;
+
+        /// <inheritdoc/>
+        private IScope AmbientScope => _scopeAccessor.AmbientScope;
+
+        /// <inheritdoc/>
+        public int CountAll()
+        {
+            Sql<ISqlContext> sql = AmbientScope.SqlContext.Sql().Select("COUNT(*)")
+                .From<CacheInstructionDto>();
+
+            return AmbientScope.Database.ExecuteScalar<int>(sql);
+        }
+
+        /// <inheritdoc/>
+        public int CountPendingInstructions(int lastId) =>
+            AmbientScope.Database.ExecuteScalar<int>("SELECT SUM(instructionCount) FROM umbracoCacheInstruction WHERE id > @lastId", new { lastId });
+
+        /// <inheritdoc/>
+        public int GetMaxId() =>
+            AmbientScope.Database.ExecuteScalar<int>("SELECT MAX(id) FROM umbracoCacheInstruction");
+
+        /// <inheritdoc/>
+        public bool Exists(int id) => AmbientScope.Database.Exists<CacheInstructionDto>(id);
+
+        /// <inheritdoc/>
+        public void Add(CacheInstruction cacheInstruction)
+        {
+            CacheInstructionDto dto = CacheInstructionFactory.BuildDto(cacheInstruction);
+            AmbientScope.Database.Insert(dto);
+        }
+
+        /// <inheritdoc/>
+        public IEnumerable<CacheInstruction> GetInstructions(int lastId, int maxNumberToRetrieve)
+        {
+            Sql<ISqlContext> sql = AmbientScope.SqlContext.Sql().SelectAll()
+                .From<CacheInstructionDto>()
+                .Where<CacheInstructionDto>(dto => dto.Id > lastId)
+                .OrderBy<CacheInstructionDto>(dto => dto.Id);
+            Sql<ISqlContext> topSql = sql.SelectTop(maxNumberToRetrieve);
+            return AmbientScope.Database.Fetch<CacheInstructionDto>(topSql).Select(CacheInstructionFactory.BuildEntity);
+        }
+
+        /// <inheritdoc/>
+        public void DeleteInstructionsOlderThan(DateTime pruneDate)
+        {
+            // Using 2 queries is faster than convoluted joins.
+            var maxId = AmbientScope.Database.ExecuteScalar<int>("SELECT MAX(id) FROM umbracoCacheInstruction;");
+            Sql deleteSql = new Sql().Append(@"DELETE FROM umbracoCacheInstruction WHERE utcStamp < @pruneDate AND id < @maxId", new { pruneDate, maxId });
+            AmbientScope.Database.Execute(deleteSql);
+        }
+    }
+}