• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 // Copyright 2014 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef TOOLS_BLINK_GC_PLUGIN_TRACING_STATUS_H_
6 #define TOOLS_BLINK_GC_PLUGIN_TRACING_STATUS_H_
7 
8 // TracingStatus is a four-point value ordered by
9 //       illegal < unneeded < unknown < needed
10 //
11 // It is used to categorize tracing of fields:
12 //
13 //  * illegal  field is invalid/illegal to trace.
14 //  * unneeded field has type with no traceable fields of its own;
15 //             it may have an empty trace() method. Not harmful
16 //             to trace, but not needed.
17 //  * unknown  initial TracingStatus value.
18 //  * needed   field is a heap reference or an object containing
19 //             traceable fields.
20 //
21 // Tracing status |illegal| is considered an error; treating |unneeded| also
22 // as an error would detect and report unnecessary tracing of objects that
23 // probably don't need to be on the Blink GC heap. However, template use
24 // and instantiation can leave us with classes that do have empty trace
25 // methods and no traceable fields -- reporting these as errors/warnings
26 // wouldn't work. Hence, only consider |illegal| as an error TracingStatus
27 // state.
28 class TracingStatus {
29  public:
Illegal()30   static TracingStatus Illegal() { return kIllegal; }
Unneeded()31   static TracingStatus Unneeded() { return kUnneeded; }
Unknown()32   static TracingStatus Unknown() { return kUnknown; }
Needed()33   static TracingStatus Needed() { return kNeeded; }
IsIllegal()34   bool IsIllegal() const { return status_ == kIllegal; }
IsUnneeded()35   bool IsUnneeded() const { return status_ == kUnneeded; }
IsUnknown()36   bool IsUnknown() const { return status_ == kUnknown; }
IsNeeded()37   bool IsNeeded() const { return status_ == kNeeded; }
LUB(const TracingStatus & other)38   TracingStatus LUB(const TracingStatus& other) const {
39     return status_ > other.status_ ? status_ : other.status_;
40   }
41   bool operator==(const TracingStatus& other) const {
42     return status_ == other.status_;
43   }
44  private:
45   enum Status { kIllegal, kUnneeded, kUnknown, kNeeded };
TracingStatus(Status status)46   TracingStatus(Status status) : status_(status) {}
47   Status status_;
48 };
49 
50 #endif // TOOLS_BLINK_GC_PLUGIN_TRACING_STATUS_H_
51