From a031b83a09a8628435317a03f199cdc18b78262f Mon Sep 17 00:00:00 2001 From: Matthew Heon Date: Wed, 1 Nov 2017 11:24:59 -0400 Subject: Initial checkin from CRI-O repo Signed-off-by: Matthew Heon --- vendor/github.com/golang/groupcache/README.md | 73 +++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) create mode 100644 vendor/github.com/golang/groupcache/README.md (limited to 'vendor/github.com/golang/groupcache/README.md') diff --git a/vendor/github.com/golang/groupcache/README.md b/vendor/github.com/golang/groupcache/README.md new file mode 100644 index 000000000..70c29da16 --- /dev/null +++ b/vendor/github.com/golang/groupcache/README.md @@ -0,0 +1,73 @@ +# groupcache + +## Summary + +groupcache is a caching and cache-filling library, intended as a +replacement for memcached in many cases. + +For API docs and examples, see http://godoc.org/github.com/golang/groupcache + +## Comparison to memcached + +### **Like memcached**, groupcache: + + * shards by key to select which peer is responsible for that key + +### **Unlike memcached**, groupcache: + + * does not require running a separate set of servers, thus massively + reducing deployment/configuration pain. groupcache is a client + library as well as a server. It connects to its own peers. + + * comes with a cache filling mechanism. Whereas memcached just says + "Sorry, cache miss", often resulting in a thundering herd of + database (or whatever) loads from an unbounded number of clients + (which has resulted in several fun outages), groupcache coordinates + cache fills such that only one load in one process of an entire + replicated set of processes populates the cache, then multiplexes + the loaded value to all callers. + + * does not support versioned values. If key "foo" is value "bar", + key "foo" must always be "bar". There are neither cache expiration + times, nor explicit cache evictions. Thus there is also no CAS, + nor Increment/Decrement. This also means that groupcache.... + + * ... supports automatic mirroring of super-hot items to multiple + processes. This prevents memcached hot spotting where a machine's + CPU and/or NIC are overloaded by very popular keys/values. + + * is currently only available for Go. It's very unlikely that I + (bradfitz@) will port the code to any other language. + +## Loading process + +In a nutshell, a groupcache lookup of **Get("foo")** looks like: + +(On machine #5 of a set of N machines running the same code) + + 1. Is the value of "foo" in local memory because it's super hot? If so, use it. + + 2. Is the value of "foo" in local memory because peer #5 (the current + peer) is the owner of it? If so, use it. + + 3. Amongst all the peers in my set of N, am I the owner of the key + "foo"? (e.g. does it consistent hash to 5?) If so, load it. If + other callers come in, via the same process or via RPC requests + from peers, they block waiting for the load to finish and get the + same answer. If not, RPC to the peer that's the owner and get + the answer. If the RPC fails, just load it locally (still with + local dup suppression). + +## Users + +groupcache is in production use by dl.google.com (its original user), +parts of Blogger, parts of Google Code, parts of Google Fiber, parts +of Google production monitoring systems, etc. + +## Presentations + +See http://talks.golang.org/2013/oscon-dl.slide + +## Help + +Use the golang-nuts mailing list for any discussion or questions. -- cgit v1.2.3-54-g00ecf