README
¶
mgopool
Package mgopool provides buffer implementations around mgo.Session (v2).
go get github.com/globalsign/mgo
go get github.com/vsco/mgopool
With mgo, an initial session is created with the server, and then either a Copy or Clone of that initial session is used for each unit of work (HTTP request handler, worker loop, etc.), which is closed upon completion. This allows mgo to efficiently manage a pool of sockets between those sessions; however, it also results in the underlying sockets to constantly log in and out of the Mongo cluster.
mgopool avoids this issue by creating a Pool of copies from the initial session, storing them in a free list. Work units request an existing copy (or one is created if it doesn't exist) and then return it to the pool on completion. Both a leaky and capped version of the Pool is available, depending on need.
Example Usage
func Example() {
// create the initial mgo.Session, defer closing it
initial, _ := mgo.Dial("127.0.0.1")
defer initial.Close()
// create a new leaky pool with size of 3
pool := mgopool.NewLeaky(initial, 3)
defer pool.Close()
wg := sync.WaitGroup{}
// create a few workers to utilize the sessions in the pool
for i := 0; i < 3; i++ {
wg.Add(1)
go func() {
for j := 0; j < 2; j++ {
// get a session from the pool
session := pool.Get()
// do something with that session, refresh it if there is an error
if err := doSomething(session); err != nil {
session.Refresh()
}
// return the session to the pool
pool.Put(session)
}
wg.Done()
}()
}
// wait for the workers to complete
wg.Wait()
// Output:
// foobar
// foobar
// foobar
// foobar
// foobar
// foobar
}
func doSomething(s *mgo.Session) error {
fmt.Println("foobar")
return s.Ping()
}
Testing
Testing mgopool requires a running Mongo cluster. The default Mongo host is used (127.0.0.1:27017) and
can be overridden by setting the MONGO_HOST env variable. Execute the tests with the following command from the project root:
script/test
License
The MIT License (MIT)
Copyright (c) 2016 Visual Supply, Co.
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Documentation
¶
Overview ¶
Package mgopool provides buffer implementations around mgo.Session (v2).
With mgo, an initial session is created with the server, and then either a copy or clone of that initial session is used for each unit of work (HTTP request handler, worker loop, etc.), which is closed upon completion. This allows mgo to efficiently manage a pool of sockets between those sessions; however, this results in the underlying sockets to constantly log in and out of the Mongo cluster.
mgopool avoids this issue by creating a Pool of copies from the initial session, storing them in a free list. Work units request an existing copy (or one is created if it doesn't exist) and then return it to the pool on completion. Both a leaky and capped version of the Pool is available, depending on need.
Example ¶
package main
import (
"os"
"sync"
"fmt"
"github.com/globalsign/mgo"
)
func main() {
host := os.Getenv("MONGO_HOST")
// create the initial mgo.Session, defer closing it
initial, _ := mgo.Dial(host)
defer initial.Close()
// create a new leaky pool with size of 3
pool := NewLeaky(initial, 3)
defer pool.Close()
wg := sync.WaitGroup{}
// create a few workers to utilize the sessions in the pool
for i := 0; i < 3; i++ {
wg.Add(1)
go func() {
for j := 0; j < 2; j++ {
// get a session from the pool
session := pool.Get()
// do something with that session, refresh it if there is an error
if err := doSomething(session); err != nil {
session.Refresh()
}
// return the session to the pool
pool.Put(session)
}
wg.Done()
}()
}
// wait for the workers to complete
wg.Wait()
}
func doSomething(s *mgo.Session) error {
fmt.Println("foobar")
return s.Ping()
}
Output: foobar foobar foobar foobar foobar foobar
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Pool ¶
type Pool interface {
// Get returns a *mgo.Session from the Pool. If there are no free sessions, a new one is copied from the initial
// Session. If the Pool is capped and all sessions have been retrieved, Get will block until a session is returned to
// with Put.
Get() *mgo.Session
// Put releases an *mgo.Session back into the Pool. Only healthy sessions (or nil) should be returned to the pool. If
// a session is errors, Refresh should be called before releasing it to the Pool.
Put(*mgo.Session)
// Used is the total number of outstanding leases associated with this Pool.
// Note, this is just a snapshot of the used leased at the time this method was invoked
Used() int
// Close drains the Pool, closing all held sessions. The initial session is not closed by this method. Calling Get or
// Put on a closed pool will result in a panic.
Close()
}
The Pool interface describes the mechanisms for retrieving and releasing mgo.Sessions. The pool should be used in place of calling Copy/Clone and Close on mgo.Session directly.
func NewCapped ¶
NewCapped creates a capped Pool of sessions copied from initial. Get on a capped Pool will block after size sessions have been retrieved until one is Put back in.
Source Files