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This changeset is meant to exemplify how to convert a "namespace" class whose
methods are static -- and whose data are module-static -- to an LLSingleton.
LLVersionInfo has no initClass() or cleanupClass() methods, but the general
idea is the same.
* Derive the class from LLSingleton<T>:
class LLSomeSingleton: public LLSingleton<LLSomeSingleton> { ... };
* Add LLSINGLETON(LLSomeSingleton); in the private section of the class. This
usage implies a separate LLSomeSingleton::LLSomeSingleton() definition, as
described in indra/llcommon/llsingleton.h.
* Move module-scope data in the .cpp file to non-static class members. Change
any sVariableName to mVariableName to avoid being outright misleading.
* Make static class methods non-static. Remove '//static' comments from method
definitions as needed.
* For LLVersionInfo specifically, the 'const std::string&' return type was
replaced with 'std::string'. Returning a reference to a static or a member,
const or otherwise, is an anti-pattern: the interface constrains the
implementation, prohibiting possibly later returning a temporary (an
expression).
* For LLVersionInfo specifically, 'const S32' return type was replaced with
simple 'S32'. 'const' is just noise in that usage.
* Simple member initialization (e.g. the original initializer expressions for
static variables) can be done with member{ value } initializers (no examples
here though).
* Delete initClass() method.
* LLSingleton's forté is of course lazy initialization. It might work to
simply delete any calls to initClass(). But if there are side effects that
must happen at that moment, replace LLSomeSingleton::initClass() with
(void)LLSomeSingleton::instance();
* Most initClass() initialization can be done in the constructor, as would
normally be the case.
* Initialization that might cause a circular LLSingleton reference should be
moved to initSingleton(). Override 'void initSingleton();' should be private.
* For LLVersionInfo specifically, certain initialization that used to be
lazily performed was made unconditional, due to its low cost.
* For LLVersionInfo specifically, certain initialization involved calling
methods that have become non-static. This was moved to initSingleton()
because, in a constructor body, 'this' does not yet point to the enclosing
class.
* Delete cleanupClass() method.
* There is already a generic LLSingletonBase::deleteAll() call in
LLAppViewer::cleanup(). It might work to let this new LLSingleton be cleaned
up with all the rest. But if there are side effects that must happen at that
moment, replace LLSomeSingleton::cleanupClass() with
LLSomeSingleton::deleteSingleton(). That said, much of the benefit of
converting to LLSingleton is deleteAll()'s guarantee that cross-LLSingleton
dependencies will be properly honored: we're trying to migrate the code base
away from the present fragile manual cleanup sequence.
* Most cleanupClass() cleanup can be done in the destructor, as would normally
be the case.
* Cleanup that might throw an exception should be moved to cleanupSingleton().
Override 'void cleanupSingleton();' should be private.
* Within LLSomeSingleton methods, remove any existing
LLSomeSingleton::methodName() qualification: simple methodName() is better.
* In the rest of the code base, convert most LLSomeSingleton::methodName()
references to LLSomeSingleton::instance().methodName(). (Prefer instance() to
getInstance() because a reference does not admit the possibility of NULL.)
* Of course, LLSomeSingleton::ENUM_VALUE can remain unchanged.
In general, for many successive references to an LLSingleton instance, it
can be useful to capture the instance() as in:
auto& versionInfo{LLVersionInfo::instance()};
// ... versionInfo.getVersion() ...
We did not do that here only to simplify the code review.
The STRINGIZE(expression) macro encapsulates:
std::ostringstream out;
out << expression;
return out.str();
We used that in a couple places.
For LLVersionInfo specifically, lllogininstance_test.cpp used to dummy out a
couple specific static methods. It's harder to dummy out
LLSingleton::instance() references, so we add the real class to that test.
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changes to common libraries from the server codebase:
* Additional error checking in http handlers.
* Uniform log spam for http errors.
* Switch to using constants for http heads and status codes.
* Fixed bugs in incorrectly checking if parsing LLSD xml resulted in an error.
* Reduced spam regarding LLSD parsing errors in the default completedRaw http handler. It should not longer be necessary to short-circuit completedRaw to avoid spam.
* Ported over a few bug fixes from the server code.
* Switch mode http status codes to use S32 instead of U32.
* Ported LLSD::asStringRef from server code; avoids copying strings all over the place.
* Ported server change to LLSD::asBinary; this always returns a reference now instead of copying the entire binary blob.
* Ported server pretty notation format (and pretty binary format) to llsd serialization.
* The new LLCurl::Responder API no longer has two error handlers to choose from. Overriding the following methods have been deprecated:
** error - use httpFailure
** errorWithContent - use httpFailure
** result - use httpSuccess
** completed - use httpCompleted
** completedHeader - no longer necessary; call getResponseHeaders() from a completion method to obtain these headers.
* In order to 'catch' a completed http request, override one of these methods:
** httpSuccess - Called for any 2xx status code.
** httpFailure - Called for any non-2xx status code.
** httpComplete - Called for all status codes. Default implementation is to call either httpSuccess or httpFailure.
* It is recommended to keep these methods protected/private in order to avoid triggering of these methods without using a 'push' method (see below).
* Uniform error handling should followed whenever possible by calling a variant of this during httpFailure:
** llwarns << dumpResponse() << llendl;
* Be sure to include LOG_CLASS(your_class_name) in your class in order for the log entry to give more context.
* In order to 'push' a result into the responder, you should no longer call error, errorWithContent, result, or completed.
* Nor should you directly call httpSuccess/Failure/Completed (unless passing a message up to a parent class).
* Instead, you can set the internal content of a responder and trigger a corresponding method using the following methods:
** successResult - Sets results and calls httpSuccess
** failureResult - Sets results and calls httpFailure
** completedResult - Sets results and calls httpCompleted
* To obtain information about a the response from a reponder method, use the following getters:
** getStatus - HTTP status code
** getReason - Reason string
** getContent - Content (Parsed body LLSD)
** getResponseHeaders - Response Headers (LLSD map)
** getHTTPMethod - HTTP method of the request
** getURL - URL of the request
* It is still possible to override completeRaw if you want to manipulate data directly out of LLPumpIO.
* See indra/llmessage/llcurl.h for more information.
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