This PR adds disk based edge caching support for minio server.
Cache settings can be configured in config.json to take list of disk drives,
cache expiry in days and file patterns to exclude from cache or via environment
variables MINIO_CACHE_DRIVES, MINIO_CACHE_EXCLUDE and MINIO_CACHE_EXPIRY
Design assumes that Atime support is enabled and the list of cache drives is
fixed.
- Objects are cached on both GET and PUT/POST operations.
- Expiry is used as hint to evict older entries from cache, or if 80% of cache
capacity is filled.
- When object storage backend is down, GET, LIST and HEAD operations fetch
object seamlessly from cache.
Current Limitations
- Bucket policies are not cached, so anonymous operations are not supported in
offline mode.
- Objects are distributed using deterministic hashing among list of cache
drives specified.If one or more drives go offline, or cache drive
configuration is altered - performance could degrade to linear lookup.
Fixes#4026
- over the course of a project history every maintainer needs to update
its dependency packages, the problem essentially with godep is manipulating
GOPATH - this manipulation leads to static objects created at different locations
which end up conflicting with the overall functionality of golang.
This also leads to broken builds. There is no easier way out of this other than
asking developers to do 'godep restore' all the time. Which perhaps as a practice
doesn't sound like a clean solution. On the other hand 'godep restore' has its own
set of problems.
- govendor is a right tool but a stop gap tool until we wait for golangs official
1.5 version which fixes this vendoring issue once and for all.
- govendor provides consistency in terms of how import paths should be handled unlike
manipulation GOPATH.
This has advantages
- no more compiled objects being referenced in GOPATH and build time GOPATH
manging which leads to conflicts.
- proper import paths referencing the exact package a project is dependent on.
govendor is simple and provides the minimal necessary tooling to achieve this.
For now this is the right solution.
poornas