From 763509589dc9933d04a26e8109f90591eef1d012 Mon Sep 17 00:00:00 2001 From: Nat Goodspeed Date: Wed, 12 Oct 2016 23:01:48 -0400 Subject: MAINT-5232: Add LLHeteroMap to contain objects of unrelated classes. --- indra/llcommon/CMakeLists.txt | 3 + indra/llcommon/llheteromap.cpp | 32 ++++++ indra/llcommon/llheteromap.h | 95 ++++++++++++++++++ indra/llcommon/tests/llheteromap_test.cpp | 158 ++++++++++++++++++++++++++++++ 4 files changed, 288 insertions(+) create mode 100644 indra/llcommon/llheteromap.cpp create mode 100644 indra/llcommon/llheteromap.h create mode 100644 indra/llcommon/tests/llheteromap_test.cpp diff --git a/indra/llcommon/CMakeLists.txt b/indra/llcommon/CMakeLists.txt index 99514fdbf7..d9ab7c1b38 100644 --- a/indra/llcommon/CMakeLists.txt +++ b/indra/llcommon/CMakeLists.txt @@ -68,6 +68,7 @@ set(llcommon_SOURCE_FILES llformat.cpp llframetimer.cpp llheartbeat.cpp + llheteromap.cpp llinitparam.cpp llinitdestroyclass.cpp llinstancetracker.cpp @@ -173,6 +174,7 @@ set(llcommon_HEADER_FILES llhandle.h llhash.h llheartbeat.h + llheteromap.h llindexedvector.h llinitdestroyclass.h llinitparam.h @@ -337,6 +339,7 @@ if (LL_TESTS) LL_ADD_INTEGRATION_TEST(llleap "" "${test_libs}") LL_ADD_INTEGRATION_TEST(llstreamqueue "" "${test_libs}") LL_ADD_INTEGRATION_TEST(llpounceable "" "${test_libs}") + LL_ADD_INTEGRATION_TEST(llheteromap "" "${test_libs}") ## llexception_test.cpp isn't a regression test, and doesn't need to be run ## every build. It's to help a developer make implementation choices about diff --git a/indra/llcommon/llheteromap.cpp b/indra/llcommon/llheteromap.cpp new file mode 100644 index 0000000000..7c19196e0c --- /dev/null +++ b/indra/llcommon/llheteromap.cpp @@ -0,0 +1,32 @@ +/** + * @file llheteromap.cpp + * @author Nat Goodspeed + * @date 2016-10-12 + * @brief Implementation for llheteromap. + * + * $LicenseInfo:firstyear=2016&license=viewerlgpl$ + * Copyright (c) 2016, Linden Research, Inc. + * $/LicenseInfo$ + */ + +// Precompiled header +#include "linden_common.h" +// associated header +#include "llheteromap.h" +// STL headers +// std headers +// external library headers +// other Linden headers + +LLHeteroMap::~LLHeteroMap() +{ + // For each entry in our map, we must call its deleter, which is the only + // record we have of its original type. + for (TypeMap::iterator mi(mMap.begin()), me(mMap.end()); mi != me; ++mi) + { + // mi->second is the std::pair; mi->second.first is the void*; + // mi->second.second points to the deleter function + (mi->second.second)(mi->second.first); + mi->second.first = NULL; + } +} diff --git a/indra/llcommon/llheteromap.h b/indra/llcommon/llheteromap.h new file mode 100644 index 0000000000..9d6f303d08 --- /dev/null +++ b/indra/llcommon/llheteromap.h @@ -0,0 +1,95 @@ +/** + * @file llheteromap.h + * @author Nat Goodspeed + * @date 2016-10-12 + * @brief Map capable of storing objects of diverse types, looked up by type. + * + * $LicenseInfo:firstyear=2016&license=viewerlgpl$ + * Copyright (c) 2016, Linden Research, Inc. + * $/LicenseInfo$ + */ + +#if ! defined(LL_LLHETEROMAP_H) +#define LL_LLHETEROMAP_H + +#include +#include // std::pair +#include + +/** + * LLHeteroMap addresses an odd requirement. Usually when you want to put + * objects of different classes into a runtime collection of any kind, you + * derive them all from a common base class and store pointers to that common + * base class. + * + * LLInitParam::BaseBlock uses disturbing raw-pointer arithmetic to find data + * members in its subclasses. It seems that no BaseBlock subclass can be + * stored in a polymorphic class of any kind: the presence of a vtbl pointer + * in the layout silently throws off the reinterpret_cast arithmetic. Bad + * Things result. (Many thanks to Nicky D for this analysis!) + * + * LLHeteroMap collects objects WITHOUT a common base class, retrieves them by + * object type and destroys them when the LLHeteroMap is destroyed. + */ +class LLHeteroMap +{ +public: + ~LLHeteroMap(); + + /// find or create + template + T& obtain() + { + // Look up map entry by typeid(T). We don't simply use mMap[typeid(T)] + // because that requires default-constructing T on every lookup. For + // some kinds of T, that could be expensive. + TypeMap::iterator found = mMap.find(&typeid(T)); + if (found == mMap.end()) + { + // Didn't find typeid(T). Create an entry. Because we're storing + // only a void* in the map, discarding type information, make sure + // we capture that type information in our deleter. + void* ptr = new T(); + void (*dlfn)(void*) = &deleter; + std::pair inserted = + mMap.insert(TypeMap::value_type(&typeid(T), + TypeMap::mapped_type(ptr, dlfn))); + // Okay, now that we have an entry, claim we found it. + found = inserted.first; + } + // found->second is the std::pair; second.first is the void* + // pointer to the object in question. Cast it to correct type and + // dereference it. + return *(static_cast(found->second.first)); + } + +private: + template + static + void deleter(void* p) + { + delete static_cast(p); + } + + // Comparing two std::type_info* values is tricky, because the standard + // does not guarantee that there will be only one type_info instance for a + // given type. In other words, &typeid(A) in one part of the program may + // not always equal &typeid(A) in some other part. Use special comparator. + struct type_info_ptr_comp + { + bool operator()(const std::type_info* lhs, const std::type_info* rhs) + { + return lhs->before(*rhs); + } + }; + + // What we actually store is a map from std::type_info (permitting lookup + // by object type) to a void* pointer to the object PLUS its deleter. + typedef std::map< + const std::type_info*, std::pair, + type_info_ptr_comp> + TypeMap; + TypeMap mMap; +}; + +#endif /* ! defined(LL_LLHETEROMAP_H) */ diff --git a/indra/llcommon/tests/llheteromap_test.cpp b/indra/llcommon/tests/llheteromap_test.cpp new file mode 100644 index 0000000000..4f38933e50 --- /dev/null +++ b/indra/llcommon/tests/llheteromap_test.cpp @@ -0,0 +1,158 @@ +/** + * @file llheteromap_test.cpp + * @author Nat Goodspeed + * @date 2016-10-12 + * @brief Test for llheteromap. + * + * $LicenseInfo:firstyear=2016&license=viewerlgpl$ + * Copyright (c) 2016, Linden Research, Inc. + * $/LicenseInfo$ + */ + +// Precompiled header +#include "linden_common.h" +// associated header +#include "llheteromap.h" +// STL headers +#include +// std headers +// external library headers +// other Linden headers +#include "../test/lltut.h" + +static std::string clog; +static std::set dlog; + +std::ostream& operator<<(std::ostream& out, const std::set& strset) +{ + out << '{'; + const char* delim = ""; + for (std::set::const_iterator si(strset.begin()), se(strset.end()); + si != se; ++si) + { + out << delim << '"' << *si << '"'; + delim = ", "; + } + out << '}'; + return out; +} + +struct Chalk +{ + int dummy; + std::string name; + + Chalk(): + dummy(0) + { + clog.append("a"); + } + + ~Chalk() + { + dlog.insert("a"); + } + +private: + Chalk(const Chalk&); // no implementation +}; + +struct Cheese +{ + std::string name; + + Cheese() + { + clog.append("e"); + } + + ~Cheese() + { + dlog.insert("e"); + } + +private: + Cheese(const Cheese&); // no implementation +}; + +struct Chowdah +{ + char displace[17]; + std::string name; + + Chowdah() + { + displace[0] = '\0'; + clog.append("o"); + } + + ~Chowdah() + { + dlog.insert("o"); + } + +private: + Chowdah(const Chowdah&); // no implementation +}; + +/***************************************************************************** +* TUT +*****************************************************************************/ +namespace tut +{ + struct llheteromap_data + { + llheteromap_data() + { + clog.erase(); + dlog.clear(); + } + }; + typedef test_group llheteromap_group; + typedef llheteromap_group::object object; + llheteromap_group llheteromapgrp("llheteromap"); + + template<> template<> + void object::test<1>() + { + set_test_name("create, get, delete"); + + { + LLHeteroMap map; + + { + // create each instance + Chalk& chalk = map.obtain(); + chalk.name = "Chalk"; + + Cheese& cheese = map.obtain(); + cheese.name = "Cheese"; + + Chowdah& chowdah = map.obtain(); + chowdah.name = "Chowdah"; + } // refs go out of scope + + { + // verify each instance + Chalk& chalk = map.obtain(); + ensure_equals(chalk.name, "Chalk"); + + Cheese& cheese = map.obtain(); + ensure_equals(cheese.name, "Cheese"); + + Chowdah& chowdah = map.obtain(); + ensure_equals(chowdah.name, "Chowdah"); + } + } // destroy map + + // Chalk, Cheese and Chowdah should have been created in specific order + ensure_equals(clog, "aeo"); + + // We don't care what order they're destroyed in, as long as each is + // appropriately destroyed. + std::set dtorset; + for (const char* cp = "aeo"; *cp; ++cp) + dtorset.insert(std::string(1, *cp)); + ensure_equals(dlog, dtorset); + } +} // namespace tut -- cgit v1.2.3