pkg/idempotent: create redis implementation

[adamdecaf]

From the X-Idempotency-Key issue (#15 (comment)) we want to implement a redis implementation of idempotent.Recorder.

Can we run an inmem redis for tests? I don't know off hand what's available.

[u5surf]

@adamdecaf
Hi. I implemented idempotent with redis (using github.com/gomodule/redigo/redis)
Refer to #15 ,I also add 1 unittest and transfers_test.
result:

$go test -v ./...
=== RUN   TestAccountType
--- PASS: TestAccountType (0.00s)
=== RUN   TestAccountType__json
--- PASS: TestAccountType__json (0.00s)
=== RUN   TestAmount
--- PASS: TestAmount (0.00s)
=== RUN   TestAmount__FromString
--- PASS: TestAmount__FromString (0.00s)
...
=== RUN   TestTransfers__transferRequest
--- PASS: TestTransfers__transferRequest (0.00s)
=== RUN   TestTransferType__json
--- PASS: TestTransferType__json (0.00s)
=== RUN   TestTransferStatus__json
--- PASS: TestTransferStatus__json (0.00s)
=== RUN   TestTransfers__idempotencyLRU
--- PASS: TestTransfers__idempotencyLRU (0.00s)
=== RUN   TestTransfers__idempotencyRedis
--- PASS: TestTransfers__idempotencyRedis (0.01s)
=== RUN   TestTransfers__getUserTransfers
--- PASS: TestTransfers__getUserTransfers (0.01s)
PASS
ok  	github.com/moov-io/paygate	0.155s
?   	github.com/moov-io/paygate/internal/version	[no test files]
=== RUN   TestACH__pingRoute
2018/10/25 12:06:11 http: multiple response.WriteHeader calls
--- PASS: TestACH__pingRoute (0.00s)
=== RUN   TestACH__buildAddress
--- PASS: TestACH__buildAddress (0.00s)
=== RUN   TestACH__addRequestHeaders
--- PASS: TestACH__addRequestHeaders (0.00s)
=== RUN   TestACH__retryWait
--- PASS: TestACH__retryWait (0.00s)
=== RUN   TestACH__retry
--- PASS: TestACH__retry (0.04s)
PASS
ok  	github.com/moov-io/paygate/pkg/achclient	0.064s
?   	github.com/moov-io/paygate/pkg/idempotent	[no test files]
=== RUN   TestLRU
--- PASS: TestLRU (0.00s)
PASS
ok  	github.com/moov-io/paygate/pkg/idempotent/lru	0.010s
=== RUN   TestLRU
--- PASS: TestLRU (0.01s)
PASS
ok  	github.com/moov-io/paygate/pkg/idempotent/redis	0.035s

But I had not considered how can we get started redis server(though, Is getting to start server scope?), proper error handling of dial and send to it(now I use panic when catch the error, I suppose to be handling as log to returns error from SeenBefore func), and a mechanism to be switching LRU which you implement and Redis yet. Don't you have any ideas following these issues?

[adamdecaf]

Thanks @u5surf!

There's https://github.com/rafaeljusto/redigomock which looks like it works with the redis library chosen too.

@wadearnold That project is GPL v2, can we use that? Probably not?
https://github.com/rafaeljusto/redigomock/blob/master/LICENSE

We defiantly don't want to panic. Returning the error with whatever context we can is helpful.

Reading the diff I noticed there's no TTL command used. We should call that as part of SET <key> <value>. The default timeout should be 24 hours. (Our docs state that already.

[u5surf]

I fixed to use context to be handling redis errors. and add defaultTimeout in redis.

[adamdecaf]

Cool! I don't think we need a context though. Can you open a PR?

[adamdecaf]

Closing, see moov-io/base#16