RedisDatabaseProvider can't re-connect

[steelmaker]

Description

I used asp.net core 3.1 application with EasyCaching.Redis 1.2.1
EasyCaching.Redis.RedisDatabaseProvider works badlly if redis not available in first request.

Steps to Reproduce

1. stop redis
2. run application
3. request to cache (easycaching) -> exception
4. start redis
5. request to cache -> exception

Related code

for my opinion problem here

private readonly Lazy<ConnectionMultiplexer> _connectionMultiplexer;

works correctly if implement like this

private Lazy<ConnectionMultiplexer> _connectionMultiplexer;
...
public IDatabase GetDatabase()
{
    try
    {
        return _connectionMultiplexer.Value.GetDatabase();
    }
    catch (Exception)
    {
        _connectionMultiplexer = new Lazy<ConnectionMultiplexer>(CreateConnectionMultiplexer);
        throw;
    }
}

Expected behavior: [What you expected to happen]

I expected cache will be work if redis available

Actual behavior: [What actually happened]

cache response exception

Specifications

• Provider : EasyCaching.Redis 1.2.1
• Interceptor : asp.net core 3.1
• Serializer : msgpack
• System : window 10

[catcherwong]

@steelmaker Thanks for your interest in this project.

PR is welcome! You can submit a PR to improve this one.