Further consolidate the libraries

grpc_pool.go

@@ -0,0 +1,83 @@
+package grpc
+
+import (
+	"sync"
+	"time"
+
+	"google.golang.org/grpc"
+)
+
+type pool struct {
+	size int
+	ttl  int64
+
+	sync.Mutex
+	conns map[string][]*poolConn
+}
+
+type poolConn struct {
+	*grpc.ClientConn
+	created int64
+}
+
+func newPool(size int, ttl time.Duration) *pool {
+	return &pool{
+		size:  size,
+		ttl:   int64(ttl.Seconds()),
+		conns: make(map[string][]*poolConn),
+	}
+}
+
+func (p *pool) getConn(addr string, opts ...grpc.DialOption) (*poolConn, error) {
+	p.Lock()
+	conns := p.conns[addr]
+	now := time.Now().Unix()
+
+	// while we have conns check age and then return one
+	// otherwise we'll create a new conn
+	for len(conns) > 0 {
+		conn := conns[len(conns)-1]
+		conns = conns[:len(conns)-1]
+		p.conns[addr] = conns
+
+		// if conn is old kill it and move on
+		if d := now - conn.created; d > p.ttl {
+			conn.ClientConn.Close()
+			continue
+		}
+
+		// we got a good conn, lets unlock and return it
+		p.Unlock()
+
+		return conn, nil
+	}
+
+	p.Unlock()
+
+	// create new conn
+	cc, err := grpc.Dial(addr, opts...)
+	if err != nil {
+		return nil, err
+	}
+
+	return &poolConn{cc, time.Now().Unix()}, nil
+}
+
+func (p *pool) release(addr string, conn *poolConn, err error) {
+	// don't store the conn if it has errored
+	if err != nil {
+		conn.ClientConn.Close()
+		return
+	}
+
+	// otherwise put it back for reuse
+	p.Lock()
+	conns := p.conns[addr]
+	if len(conns) >= p.size {
+		p.Unlock()
+		conn.ClientConn.Close()
+		return
+	}
+	p.conns[addr] = append(conns, conn)
+	p.Unlock()
+}