92 lines
2.3 KiB
Go
92 lines
2.3 KiB
Go
// Copyright 2020 Google LLC.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package grpc
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import (
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"context"
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"fmt"
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"sync/atomic"
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"google.golang.org/api/internal"
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"google.golang.org/grpc"
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)
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// ConnPool is a pool of grpc.ClientConns.
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type ConnPool = internal.ConnPool // NOTE(cbro): type alias to export the type. It must live in internal to avoid a circular dependency.
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var _ ConnPool = &roundRobinConnPool{}
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var _ ConnPool = &singleConnPool{}
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// singleConnPool is a special case for a single connection.
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type singleConnPool struct {
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*grpc.ClientConn
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}
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func (p *singleConnPool) Conn() *grpc.ClientConn { return p.ClientConn }
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func (p *singleConnPool) Num() int { return 1 }
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type roundRobinConnPool struct {
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conns []*grpc.ClientConn
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idx uint32 // access via sync/atomic
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}
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func (p *roundRobinConnPool) Num() int {
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return len(p.conns)
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}
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func (p *roundRobinConnPool) Conn() *grpc.ClientConn {
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i := atomic.AddUint32(&p.idx, 1)
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return p.conns[i%uint32(len(p.conns))]
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}
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func (p *roundRobinConnPool) Close() error {
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var errs multiError
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for _, conn := range p.conns {
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if err := conn.Close(); err != nil {
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errs = append(errs, err)
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}
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}
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if len(errs) == 0 {
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return nil
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}
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return errs
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}
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func (p *roundRobinConnPool) Invoke(ctx context.Context, method string, args interface{}, reply interface{}, opts ...grpc.CallOption) error {
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return p.Conn().Invoke(ctx, method, args, reply, opts...)
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}
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func (p *roundRobinConnPool) NewStream(ctx context.Context, desc *grpc.StreamDesc, method string, opts ...grpc.CallOption) (grpc.ClientStream, error) {
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return p.Conn().NewStream(ctx, desc, method, opts...)
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}
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// multiError represents errors from multiple conns in the group.
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//
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// TODO: figure out how and whether this is useful to export. End users should
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// not be depending on the transport/grpc package directly, so there might need
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// to be some service-specific multi-error type.
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type multiError []error
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func (m multiError) Error() string {
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s, n := "", 0
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for _, e := range m {
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if e != nil {
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if n == 0 {
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s = e.Error()
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}
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n++
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}
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}
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switch n {
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case 0:
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return "(0 errors)"
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case 1:
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return s
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case 2:
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return s + " (and 1 other error)"
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}
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return fmt.Sprintf("%s (and %d other errors)", s, n-1)
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}
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