github.com/blixtra/rkt@v0.8.1-0.20160204105720-ab0d1add1a43/Godeps/_workspace/src/google.golang.org/grpc/naming/naming.go (about)

     1  /*
     2   *
     3   * Copyright 2014, Google Inc.
     4   * All rights reserved.
     5   *
     6   * Redistribution and use in source and binary forms, with or without
     7   * modification, are permitted provided that the following conditions are
     8   * met:
     9   *
    10   *     * Redistributions of source code must retain the above copyright
    11   * notice, this list of conditions and the following disclaimer.
    12   *     * Redistributions in binary form must reproduce the above
    13   * copyright notice, this list of conditions and the following disclaimer
    14   * in the documentation and/or other materials provided with the
    15   * distribution.
    16   *     * Neither the name of Google Inc. nor the names of its
    17   * contributors may be used to endorse or promote products derived from
    18   * this software without specific prior written permission.
    19   *
    20   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    21   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    22   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    23   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    24   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    25   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    26   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    27   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    28   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    29   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    30   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    31   *
    32   */
    33  
    34  // Package naming defines the naming API and related data structures for gRPC.
    35  // The interface is EXPERIMENTAL and may be suject to change.
    36  package naming
    37  
    38  // Operation defines the corresponding operations for a name resolution change.
    39  type Operation uint8
    40  
    41  const (
    42  	// Add indicates a new address is added.
    43  	Add Operation = iota
    44  	// Delete indicates an exisiting address is deleted.
    45  	Delete
    46  )
    47  
    48  // Update defines a name resolution update. Notice that it is not valid having both
    49  // empty string Addr and nil Metadata in an Update.
    50  type Update struct {
    51  	// Op indicates the operation of the update.
    52  	Op Operation
    53  	// Addr is the updated address. It is empty string if there is no address update.
    54  	Addr string
    55  	// Metadata is the updated metadata. It is nil if there is no metadata update.
    56  	// Metadata is not required for a custom naming implementation.
    57  	Metadata interface{}
    58  }
    59  
    60  // Resolver creates a Watcher for a target to track its resolution changes.
    61  type Resolver interface {
    62  	// Resolve creates a Watcher for target.
    63  	Resolve(target string) (Watcher, error)
    64  }
    65  
    66  // Watcher watches for the updates on the specified target.
    67  type Watcher interface {
    68  	// Next blocks until an update or error happens. It may return one or more
    69  	// updates. The first call should get the full set of the results.
    70  	Next() ([]*Update, error)
    71  	// Close closes the Watcher.
    72  	Close()
    73  }