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author | Feng Xiao <xfxyjwf@gmail.com> | 2016-07-14 15:33:45 -0700 |
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committer | Feng Xiao <xfxyjwf@gmail.com> | 2016-07-14 15:33:45 -0700 |
commit | 1bce70dddb57aa82c3e6a74b072f6a742f47c900 (patch) | |
tree | 9f6b012f5f0d3904ab15ed94ed2ff0405a895358 /protobuf.pc.in | |
parent | 0b6825516b403ce7f9c830074d3cbb5477b4c6a1 (diff) | |
download | protobuf-1bce70dddb57aa82c3e6a74b072f6a742f47c900.tar.gz protobuf-1bce70dddb57aa82c3e6a74b072f6a742f47c900.tar.bz2 protobuf-1bce70dddb57aa82c3e6a74b072f6a742f47c900.zip |
Fix compatiblity issues.
Currently some public API methods are defined in GenreatedMessage.java
and they have a generric return type:
class GeneratedMessage {
class Builder<BuilderType extends Builder<BuilderType>> {
public BuilderType setField(...);
public BuilderType setExtension(...);
}
}
With these definitions, the compiled byte code of a callsite will have
a direct reference to GeneratedMessage. For example:
fooBuilder.setField(...);
becomes:
##: invokevirtual // Method Builder.setField:(...)LGeneratedMessage.Builder
##: checkcast // class Builder
This will prevent us from updating generated classes to subclass a
different versioned GeneratedMessageV3 class in the future (we can't do
it in a binary compatible way).
This change addresses the problem by overriding these methods directly
in the generated class:
class Foo {
class Builder extends GeneratedMessage.Builder<Builder> {
public Builder setField(...) {
return super.setField(...);
}
}
}
After this, fooBuilder.setField(...) will be compiled to:
##: invokevirtual // Method Builder.setField:(...)LFoo.Builder
The callsites will no longer reference GeneratedMessage directly and we
can change Foo to subclass GeneratedMessageV3 without breaking binary
compatiblity.
The downside of this change is:
1. It increases generated code size (though it saves some instructions
on the callsites).
2. We can never stop generating these overrides because doing that
will break binary compatibility.
Change-Id: I879afbbc1325a66324a51565e017143489b06e97
Diffstat (limited to 'protobuf.pc.in')
0 files changed, 0 insertions, 0 deletions