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Make loadLibrary()/unloadLibrary() safe against concurrent load and unload #234

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Merged
clalancette merged 1 commit into from
Sep 2, 2026
+16 −4
Merged

Make loadLibrary()/unloadLibrary() safe against concurrent load and unload #234

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20 changes: 16 additions & 4 deletions src/class_loader_core.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,16 @@ std::recursive_mutex & getPluginBaseToFactoryMapMapMutex()
return m;
}

namespace
{
// Serializes loadLibrary()/unloadLibrary() so a dlopen() never overlaps a dlclose().
std::recursive_mutex & getLoaderMutex()
{
static std::recursive_mutex m;
return m;
}
} // namespace

BaseToFactoryMapMap & getGlobalPluginBaseToFactoryMapMap()
{
static BaseToFactoryMapMap instance;
Expand Down Expand Up @@ -390,13 +400,16 @@ void purgeGraveyardOfMetaobjects(

void loadLibrary(const std::string & library_path, ClassLoader * loader)
{
std::lock_guard<std::recursive_mutex> loader_lock(getLoaderMutex());

CONSOLE_BRIDGE_logDebug(
"class_loader.impl: "
"Attempting to load library %s on behalf of ClassLoader handle %p...\n",
library_path.c_str(), reinterpret_cast<void *>(loader));

// If it's already open, just update existing metaobjects to have an additional owner.
if (isLibraryLoadedByAnybody(library_path)) {
std::lock_guard<std::recursive_mutex> lock(getPluginBaseToFactoryMapMapMutex());
CONSOLE_BRIDGE_logDebug(
"%s",
"class_loader.impl: "
Expand All @@ -407,11 +420,7 @@ void loadLibrary(const std::string & library_path, ClassLoader * loader)

std::shared_ptr<rcpputils::SharedLibrary> library_handle;

static std::recursive_mutex loader_mutex;

{
std::lock_guard<std::recursive_mutex> loader_lock(loader_mutex);

setCurrentlyActiveClassLoader(loader);
setCurrentlyLoadingLibraryName(library_path);
try {
Expand Down Expand Up @@ -463,6 +472,8 @@ void loadLibrary(const std::string & library_path, ClassLoader * loader)

void unloadLibrary(const std::string & library_path, ClassLoader * loader)
{
std::lock_guard<std::recursive_mutex> loader_lock(getLoaderMutex());

if (hasANonPurePluginLibraryBeenOpened()) {
CONSOLE_BRIDGE_logDebug(
"class_loader.impl: "
Expand All @@ -479,6 +490,7 @@ void unloadLibrary(const std::string & library_path, ClassLoader * loader)
"Unloading library %s on behalf of ClassLoader %p...",
library_path.c_str(), reinterpret_cast<void *>(loader));

std::lock_guard<std::recursive_mutex> llv_lock(getLoadedLibraryVectorMutex());
LibraryVector & open_libraries = getLoadedLibraryVector();
LibraryVector::iterator itr = findLoadedLibrary(library_path);
if (itr != open_libraries.end()) {
Expand Down
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