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// Copyright Epic Games, Inc. All Rights Reserved.
#include "zenutil/openprocesscache.h"
#include <zencore/fmtutils.h>
#include <zencore/logging.h>
#include <zencore/memory/llm.h>
#if ZEN_PLATFORM_WINDOWS
# include <zencore/windows.h>
#else
# include <sys/mman.h>
#endif
//////////////////////////////////////////////////////////////////////////
namespace zen {
const FLLMTag&
GetProcCacheTag()
{
static FLLMTag CacheHttpTag("proccache");
return CacheHttpTag;
}
OpenProcessCache::OpenProcessCache()
#if ZEN_PLATFORM_WINDOWS
: m_GcThread(&OpenProcessCache::GcWorker, this)
#endif // ZEN_PLATFORM_WINDOWS
{
}
OpenProcessCache::~OpenProcessCache()
{
#if ZEN_PLATFORM_WINDOWS
try
{
m_GcExitEvent.Set();
if (m_GcThread.joinable())
{
m_GcThread.join();
}
RwLock::ExclusiveLockScope Lock(m_SessionsLock);
for (const auto& It : m_Sessions)
{
if (It.second.ProcessHandle == nullptr)
{
continue;
}
CloseHandle(It.second.ProcessHandle);
}
m_Sessions.clear();
}
catch (const std::exception& Ex)
{
ZEN_ERROR("OpenProcessCache destructor failed with reason: `{}`", Ex.what());
}
#endif // ZEN_PLATFORM_WINDOWS
}
void*
OpenProcessCache::GetProcessHandle(Oid SessionId, int ProcessPid)
{
if (ProcessPid == 0)
{
return nullptr;
}
if (SessionId == Oid::Zero)
{
return nullptr;
}
ZEN_MEMSCOPE(GetProcCacheTag());
#if ZEN_PLATFORM_WINDOWS
ZEN_ASSERT(ProcessPid != 0);
{
RwLock::SharedLockScope Lock(m_SessionsLock);
if (auto It = m_Sessions.find(SessionId); It != m_Sessions.end())
{
if (ProcessPid == It->second.ProcessPid)
{
void* ProcessHandle = It->second.ProcessHandle;
if (ProcessHandle == nullptr)
{
// Session is stale, just ignore it
return nullptr;
}
DWORD ExitCode = 0;
GetExitCodeProcess(ProcessHandle, &ExitCode);
if (ExitCode == STILL_ACTIVE)
{
return ProcessHandle;
}
}
}
}
void* ProcessHandle = nullptr;
void* DeadHandle = nullptr;
{
// Add/replace the session
RwLock::ExclusiveLockScope Lock(m_SessionsLock);
if (auto It = m_Sessions.find(SessionId); It != m_Sessions.end())
{
// Check to see if someone beat us to it...
if ((It->second.ProcessHandle != nullptr) && (ProcessPid == It->second.ProcessPid))
{
DWORD ExitCode = 0;
GetExitCodeProcess(It->second.ProcessHandle, &ExitCode);
if (ExitCode == STILL_ACTIVE)
{
return It->second.ProcessHandle;
}
}
ZEN_INFO("Purging stale target process pid {} for session: {}", It->second.ProcessPid, SessionId, It->second.ProcessHandle);
DeadHandle = It->second.ProcessHandle;
m_Sessions.erase(It);
}
// Cache new handle
ProcessHandle = OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION | PROCESS_DUP_HANDLE, FALSE, ProcessPid);
ZEN_INFO("Opened target process pid {} for session {}: {}", ProcessPid, SessionId, ProcessHandle == nullptr ? "failed" : "success");
m_Sessions.insert_or_assign(SessionId, Process{.ProcessPid = ProcessPid, .ProcessHandle = ProcessHandle});
}
if (DeadHandle != nullptr)
{
CloseHandle(DeadHandle);
}
return ProcessHandle;
#else // ZEN_PLATFORM_WINDOWS
ZEN_UNUSED(SessionId);
return nullptr;
#endif // ZEN_PLATFORM_WINDOWS
}
#if ZEN_PLATFORM_WINDOWS
void
OpenProcessCache::GCHandles()
{
std::vector<void*> DeadHandles;
{
std::vector<Oid> DeadSessions;
RwLock::ExclusiveLockScope Lock(m_SessionsLock);
for (auto& It : m_Sessions)
{
if (It.second.ProcessHandle == nullptr)
{
// Stale session, remove it on second pass of GC
DeadSessions.push_back(It.first);
continue;
}
ZEN_ASSERT(It.second.ProcessPid != 0);
DWORD ExitCode = 0;
GetExitCodeProcess(It.second.ProcessHandle, &ExitCode);
if (ExitCode == STILL_ACTIVE)
{
continue;
}
ZEN_INFO("GC stale target process pid {} for session {}: {}", It.second.ProcessPid, It.first, It.second.ProcessHandle);
DeadHandles.push_back(It.second.ProcessHandle);
// We just mark the session as "dead" for one GC pass to avoid re-opening a stale process
It.second.ProcessHandle = nullptr;
}
for (auto SessionId : DeadSessions)
{
ZEN_INFO("Purging stale target process cache for session: {}", SessionId);
m_Sessions.erase(SessionId);
}
}
for (auto Handle : DeadHandles)
{
CloseHandle(Handle);
}
}
void
OpenProcessCache::GcWorker()
{
ZEN_MEMSCOPE(GetProcCacheTag());
SetCurrentThreadName("ProcessCache_GC");
while (!m_GcExitEvent.Wait(500))
{
try
{
GCHandles();
}
catch (const std::exception& Ex)
{
ZEN_ERROR("gc of open process cache failed with reason: `{}`", Ex.what());
}
}
}
#endif // ZEN_PLATFORM_WINDOWS
} // namespace zen
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