| /* |
| * |
| * Copyright 2014, Google Inc. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following disclaimer |
| * in the documentation and/or other materials provided with the |
| * distribution. |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| * |
| */ |
| |
| package grpc |
| |
| import ( |
| "time" |
| |
| "golang.org/x/net/context" |
| "google.golang.org/grpc/transport" |
| ) |
| |
| // Picker picks a Conn for RPC requests. |
| // This is EXPERIMENTAL and please do not implement your own Picker for now. |
| type Picker interface { |
| // Init does initial processing for the Picker, e.g., initiate some connections. |
| Init(cc *ClientConn) error |
| // Pick blocks until either a transport.ClientTransport is ready for the upcoming RPC |
| // or some error happens. |
| Pick(ctx context.Context) (transport.ClientTransport, error) |
| // State returns the connectivity state of the underlying connections. |
| State() ConnectivityState |
| // WaitForStateChange blocks until the state changes to something other than |
| // the sourceState or timeout fires on cc. It returns false if timeout fires, |
| // and true otherwise. |
| WaitForStateChange(timeout time.Duration, sourceState ConnectivityState) bool |
| // Close closes all the Conn's owned by this Picker. |
| Close() error |
| } |
| |
| // unicastPicker is the default Picker which is used when there is no custom Picker |
| // specified by users. It always picks the same Conn. |
| type unicastPicker struct { |
| conn *Conn |
| } |
| |
| func (p *unicastPicker) Init(cc *ClientConn) error { |
| c, err := NewConn(cc) |
| if err != nil { |
| return err |
| } |
| p.conn = c |
| return nil |
| } |
| |
| func (p *unicastPicker) Pick(ctx context.Context) (transport.ClientTransport, error) { |
| return p.conn.Wait(ctx) |
| } |
| |
| func (p *unicastPicker) State() ConnectivityState { |
| return p.conn.State() |
| } |
| |
| func (p *unicastPicker) WaitForStateChange(timeout time.Duration, sourceState ConnectivityState) bool { |
| return p.conn.WaitForStateChange(timeout, sourceState) |
| } |
| |
| func (p *unicastPicker) Close() error { |
| if p.conn != nil { |
| return p.conn.Close() |
| } |
| return nil |
| } |