1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
|
// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <vespa/messagebus/common.h>
#include <vespa/fnet/frt/invoker.h>
#include <vespa/fnet/frt/target.h>
#include <vespa/vespalib/component/version.h>
namespace mbus {
/**
* Implements a target object that encapsulates the FRT connection
* target. Instances of this class are returned by {@link RPCService}, and
* cached by {@link RPCTargetPool}.
*/
class RPCTarget : public FRT_IRequestWait, public std::enable_shared_from_this<RPCTarget> {
public:
/**
* Declares a version handler used when resolving the version of a target.
* An instance of this is passed to {@link RPCTarget#resolveVersion(double,
* VersionHandler)}, and invoked either synchronously or asynchronously,
* depending on whether or not the version is already available.
*/
class IVersionHandler {
public:
/**
* Virtual destructor required for inheritance.
*/
virtual ~IVersionHandler() = default;
/**
* This method is invoked once the version of the corresponding {@link
* RPCTarget} becomes available. If a problem occurred while retrieving
* the version, this method is invoked with a null argument.
*
* @param ver The version of corresponding target, or null.
*/
virtual void handleVersion(const vespalib::Version *ver) = 0;
};
private:
using HandlerList = std::vector<IVersionHandler*>;
enum ResolveState {
VERSION_NOT_RESOLVED,
TARGET_INVOKED,
PROCESSING_HANDLERS,
VERSION_RESOLVED,
};
using Version_UP = std::unique_ptr<vespalib::Version>;
std::mutex _lock;
std::condition_variable _cond;
FRT_Supervisor &_orb;
string _name;
FRT_Target &_target;
std::atomic<ResolveState> _state;
Version_UP _version;
HandlerList _versionHandlers;
struct ctor_tag {};
public:
/**
* Convenience typedefs.
*/
using SP = std::shared_ptr<RPCTarget>;
/**
* Constructs a new instance of this class. This object creates and
* takes ownership of a corresponding FRT target, and will deref it
* upon destruction.
*
* @param spec The connection spec of this target.
* @param orb The FRT supervisor to use when connecting to target.
*/
RPCTarget(const string &name, FRT_Supervisor &orb, ctor_tag);
static SP create(const string &name, FRT_Supervisor &orb) {
return std::make_shared<RPCTarget>(name, orb, ctor_tag{});
}
/**
* Destructor. Subrefs the contained FRT target.
*/
~RPCTarget();
/**
* Requests the version of this target be passed to the given {@link
* VersionHandler}. If the version is available, the handler is called
* synchronously; if not, the handler is called by the network thread once
* the target responds to the version query.
*
* @param timeout The timeout for the request in milliseconds.
* @param handler The handler to be called once the version is available.
*/
void resolveVersion(duration timeout, IVersionHandler &handler);
/**
* @return true if the FRT target is valid or has been invoked (which
* means we cannot destroy it).
*/
bool isValid() const;
/**
* Returns the encapsulated FRT target.
*
* @return The target.
*/
FRT_Target &getFRTTarget() { return _target; }
/**
* Returns the version to use when communicating with this target.
* Version must have been successfully resolved before calling this
* function.
*
* @return The negotiated version.
*/
const vespalib::Version &getVersion() const { return *_version; }
// Implements FRT_IRequestWait.
void RequestDone(FRT_RPCRequest *req) override;
};
} // namespace mbus
|
