Added support for DeleteExpiredBatchSize in PostgreSqlStorageOptions to make it configurable from the default of 1000 items

This setting determines how many expired items we attempt to delete from our Hangfire processing tables per run

Author: Plasma

src/Hangfire.PostgreSql/ExpirationManager.cs

@@ -32,7 +32,6 @@ namespace Hangfire.PostgreSql
     internal class ExpirationManager : IBackgroundProcess, IServerComponent
     {
         private static readonly TimeSpan DelayBetweenPasses = TimeSpan.FromSeconds(1);
-        private const int NumberOfRecordsInSinglePass = 1000;
 
         private static readonly ILog Logger = LogProvider.GetLogger(typeof(ExpirationManager));
 
@@ -93,7 +92,7 @@ DELETE FROM """ + _options.SchemaName + @""".""{0}""
     FROM """ + _options.SchemaName + @""".""{0}"" 
     WHERE ""expireat"" < NOW() AT TIME ZONE 'UTC' 
     LIMIT {1}
-)", table, NumberOfRecordsInSinglePass.ToString(CultureInfo.InvariantCulture)), transaction);
+)", table, _options.DeleteExpiredBatchSize.ToString(CultureInfo.InvariantCulture)), transaction);
 
                             transaction.Commit();
                         }

src/Hangfire.PostgreSql/PostgreSqlStorageOptions.cs

@@ -30,6 +30,7 @@ public class PostgreSqlStorageOptions
         private TimeSpan _distributedLockTimeout;
         private TimeSpan _transactionSerializationTimeout;
         private TimeSpan _jobExpirationCheckInterval;
+        private int _deleteExpiredBatchSize;
 
         public PostgreSqlStorageOptions()
         {
@@ -41,6 +42,7 @@ public PostgreSqlStorageOptions()
             SchemaName = "hangfire";
             UseNativeDatabaseTransactions = true;
             PrepareSchemaIfNecessary = true;
+            DeleteExpiredBatchSize = 1000;
         }
 
         public TimeSpan QueuePollInterval
@@ -93,7 +95,20 @@ public TimeSpan JobExpirationCheckInterval
 			}
 		}
 
-        public bool UseNativeDatabaseTransactions { get; set; }
+		/// <summary>
+		/// Gets or sets the number of records deleted in a single batch in expiration manager
+		/// </summary>
+		public int DeleteExpiredBatchSize
+		{
+			get => _deleteExpiredBatchSize;
+			set 
+			{
+				ThrowIfValueIsNotPositive(value, nameof(DeleteExpiredBatchSize));
+                _deleteExpiredBatchSize = value;
+			}
+		}
+
+		public bool UseNativeDatabaseTransactions { get; set; }
         public bool PrepareSchemaIfNecessary { get; set; }
         public string SchemaName { get; set; }
         public bool EnableTransactionScopeEnlistment { get; set; }
@@ -111,5 +126,11 @@ private static void ThrowIfValueIsNotPositive(TimeSpan value, string fieldName)
                 throw new ArgumentException(message, nameof(value));
             }
         }
+
+        private static void ThrowIfValueIsNotPositive(int value, string fieldName)
+        {
+            if (value < 0)
+		        throw new ArgumentException($"The {fieldName} property value should be positive. Given: {value}.");
+        }
     }
 }