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New cache implementation and prefetch handing in mw/cache (#731)

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* cache: add sharded cache implementation

Add Cache impl and a few tests. This cache is 256-way sharded, mainly
so each shard has it's own lock. The main cache structure is a readonly
jump plane into the right shard.

This should remove the single lock contention on the main lock and
provide more concurrent throughput - Obviously this hasn't been tested
or measured.

The key into the cache was made a uint32 (hash.fnv) and the hashing op
is not using strings.ToLower anymore remove any GC in that code path.

* here too

* Minimum shard size

* typos

* blurp

* small cleanups no defer

* typo

* Add freq based on Johns idea

* cherry-pick conflict resolv

* typo

* update from early code review from john

* add prefetch to the cache

* mw/cache: add prefetch

* remove println

* remove comment

* Fix tests

* Test prefetch in setup

* Add start of cache

* try add diff cache options

* Add hacky testcase

* not needed

* allow the use of a percentage for prefetch

If the TTL falls below xx% do a prefetch, if the record was popular.
Some other fixes and correctly prefetch only popular records.
This commit is contained in:
Miek Gieben 2017-06-13 12:39:10 -07:00 • committed by GitHub
parent b1efd3736e
commit e9eda7e7c8
23 changed files with 595 additions and 142 deletions
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55
middleware/cache/setup.go vendored
View file

@ -7,8 +7,8 @@ import (
"github.com/coredns/coredns/core/dnsserver"
"github.com/coredns/coredns/middleware"
"github.com/coredns/coredns/middleware/pkg/cache"
"github.com/hashicorp/golang-lru"
"github.com/mholt/caddy"
)
@ -38,7 +38,7 @@ func setup(c *caddy.Controller) error {
func cacheParse(c *caddy.Controller) (*Cache, error) {
ca := &Cache{pcap: defaultCap, ncap: defaultCap, pttl: maxTTL, nttl: maxNTTL}
ca := &Cache{pcap: defaultCap, ncap: defaultCap, pttl: maxTTL, nttl: maxNTTL, prefetch: 0, duration: 1 * time.Minute}
for c.Next() {
// cache [ttl] [zones..]
@ -109,6 +109,46 @@ func cacheParse(c *caddy.Controller) (*Cache, error) {
}
ca.nttl = time.Duration(nttl) * time.Second
}
case "prefetch":
args := c.RemainingArgs()
if len(args) == 0 || len(args) > 3 {
return nil, c.ArgErr()
}
amount, err := strconv.Atoi(args[0])
if err != nil {
return nil, err
}
if amount < 0 {
return nil, fmt.Errorf("prefetch amount should be positive: %d", amount)
}
ca.prefetch = amount
ca.duration = 1 * time.Minute
ca.percentage = 10
if len(args) > 1 {
dur, err := time.ParseDuration(args[1])
if err != nil {
return nil, err
}
ca.duration = dur
}
if len(args) > 2 {
pct := args[2]
if x := pct[len(pct)-1]; x != '%' {
return nil, fmt.Errorf("last character of percentage should be `%%`, but is: %q", x)
}
pct = pct[:len(pct)-1]
num, err := strconv.Atoi(pct)
if err != nil {
return nil, err
}
if num < 10 || num > 90 {
return nil, fmt.Errorf("percentage should fall in range [10, 90]: %d", num)
}
ca.percentage = num
}
default:
return nil, c.ArgErr()
}
@ -118,17 +158,10 @@ func cacheParse(c *caddy.Controller) (*Cache, error) {
origins[i] = middleware.Host(origins[i]).Normalize()
}
var err error
ca.Zones = origins
ca.pcache, err = lru.New(ca.pcap)
if err != nil {
return nil, err
}
ca.ncache, err = lru.New(ca.ncap)
if err != nil {
return nil, err
}
ca.pcache = cache.New(ca.pcap)
ca.ncache = cache.New(ca.ncap)
return ca, nil
}