Orchard/src/Orchard.Web/Modules/Orchard.Redis/Extensions/RedisDatabaseExtensions.cs

using System;
using StackExchange.Redis;

namespace Orchard.Redis.Extensions {
    public static class RedisDatabaseExtensions {

        public static void KeyDeleteWithPrefix(this IDatabase database, string prefix) {
            if (database == null) {
                throw new ArgumentException("Database cannot be null", "database");
            }

            if (string.IsNullOrWhiteSpace(prefix)) {
                throw new ArgumentException("Prefix cannot be empty", "database");
            }

            database.ScriptEvaluate(@"
                local keys = redis.call('keys', ARGV[1]) 
                for i=1,#keys,5000 do 
                redis.call('del', unpack(keys, i, math.min(i+4999, #keys)))
                end", values: new RedisValue[] { prefix });
        }

        public static int KeyCount(this IDatabase database, string prefix) {
            if (database == null) {
                throw new ArgumentException("Database cannot be null", "database");
            }

            if (string.IsNullOrWhiteSpace(prefix)) {
                throw new ArgumentException("Prefix cannot be empty", "database");
            }

            var retVal = database.ScriptEvaluate("return table.getn(redis.call('keys', ARGV[1]))", values: new RedisValue[] { prefix });

            if (retVal.IsNull) {
                return 0;
            }

            return (int)retVal;
        }
    }
}