thread.h

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/*
 * thread.h: A simple thread base class
 *
 * See the main source file 'vdr.c' for copyright information and
 * how to reach the author.
 *
 * $Id: thread.h 5.2 2026/08/22 11:23:08 kls Exp $
 */
 
#ifndef __THREAD_H
#define __THREAD_H
 
#include <atomic>
#include <pthread.h>
#include <stdio.h>
#include <sys/types.h>
 
typedef pid_t tThreadId;
 
class cCondWait {
private:
  pthread_mutex_t mutex;
  pthread_cond_t cond;
  bool signaled;
public:
  cCondWait(void);
  ~cCondWait();
  static void SleepMs(int TimeoutMs);
  bool Wait(int TimeoutMs = 0);
  void Signal(void);
  };
 
class cMutex;
 
class cCondVar {
private:
  pthread_cond_t cond;
public:
  cCondVar(void);
  ~cCondVar();
  void Wait(cMutex &Mutex);
  bool TimedWait(cMutex &Mutex, int TimeoutMs);
  void Broadcast(void);
  };
 
class cRwLock {
private:
  pthread_rwlock_t rwlock;
  int locked;
  std::atomic<tThreadId> writeLockThreadId; // Lock() reads it without holding the lock
public:
  cRwLock(bool PreferWriter = false);
  ~cRwLock();
  bool Lock(bool Write, int TimeoutMs = 0);
  void Unlock(void);
  };
 
class cMutex {
  friend class cCondVar;
private:
  pthread_mutex_t mutex;
  std::atomic<tThreadId> lockThreadId; // current holder, 0 == unlocked; lets Lock() short-circuit recursive entry (read without holding the mutex)
  int locked;
public:
  cMutex(void);
  ~cMutex();
  bool Lock(int TimeoutMs = 0, bool * TimedOut = NULL);
  void Unlock(void);
  };
 
class cThread {
  friend class cThreadLock;
private:
  // Shared by the thread and those that start, poll or cancel it; whoever
  // sees 'active' false must also see everything Action() did:
  std::atomic<bool> active;
  std::atomic<bool> running;
  pthread_t childTid;
  std::atomic<tThreadId> childThreadId; // set by the thread itself, logged by Cancel()
  cMutex mutex;
  char *description;
  bool lowPriority;
  static tThreadId mainThreadId;
  static void *StartThread(cThread *Thread);
protected:
  void SetPriority(int Priority);
  void SetIOPriority(int Priority);
  void Lock(void) { mutex.Lock(); }
  void Unlock(void) { mutex.Unlock(); }
  virtual void Action(void) = 0;
  bool Running(void) { return running; }
  void Cancel(int WaitSeconds = 0);
public:
  cThread(const char *Description = NULL, bool LowPriority = false);
  virtual ~cThread();
  void SetDescription(const char *Description, ...) __attribute__ ((format (printf, 2, 3)));
  bool Start(void);
  bool Active(void);
  static tThreadId ThreadId(void);
  static tThreadId IsMainThread(void) { return ThreadId() == mainThreadId; }
  static void SetMainThreadId(void);
  };
 
// cMutexLock can be used to easily set a lock on mutex and make absolutely
// sure that it will be unlocked when the block will be left. Several locks can
// be stacked, so a function that makes many calls to another function which uses
// cMutexLock may itself use a cMutexLock to make one longer lock instead of many
// short ones.
 
class cMutexLock {
private:
  cMutex *mutex;
  bool locked;
public:
  cMutexLock(cMutex *Mutex = NULL);
  ~cMutexLock();
  bool Lock(cMutex *Mutex, int TimeoutMs = 0, bool *TimedOut = NULL);
  };
 
// cThreadLock can be used to easily set a lock in a thread and make absolutely
// sure that it will be unlocked when the block will be left. Several locks can
// be stacked, so a function that makes many calls to another function which uses
// cThreadLock may itself use a cThreadLock to make one longer lock instead of many
// short ones.
 
class cThreadLock {
private:
  cThread *thread;
  bool locked;
public:
  cThreadLock(cThread *Thread = NULL);
  ~cThreadLock();
  bool Lock(cThread *Thread);
  };
 
#define LOCK_THREAD cThreadLock ThreadLock(this)
 
class cStateKey;
 
class cStateLock {
  friend class cStateKey;
private:
  enum { emDisabled = 0, emArmed, emEnabled };
  const char *name;
  tThreadId threadId;
  cRwLock rwLock;
  int state;
  int explicitModify;
  cStateKey *syncStateKey;
  void Unlock(cStateKey &StateKey, bool IncState = true);
public:
  cStateLock(const char *Name = NULL);
  bool Lock(cStateKey &StateKey, bool Write = false, int TimeoutMs = 0);
  void SetSyncStateKey(cStateKey &StateKey);
  void SetExplicitModify(void);
  void SetModified(void);
  };
 
class cStateKey {
  friend class cStateLock;
private:
  cStateLock *stateLock;
  bool write;
  int state;
  bool timedOut;
public:
  cStateKey(bool IgnoreFirst = false);
  ~cStateKey();
  void Reset(void);
  void Remove(bool IncState = true);
  bool StateChanged(void);
  bool InLock(void) { return stateLock; }
  bool TimedOut(void) const { return timedOut; }
  };
 
class cIoThrottle {
private:
  static cMutex mutex;
  static std::atomic<int> count; // Engaged() reads it without the mutex
  bool active;
public:
  cIoThrottle(void);
  ~cIoThrottle();
  void Activate(void);
  void Release(void);
  bool Active(void) { return active; }
  static bool Engaged(void);
  };
 
// cPipe implements a pipe that closes all unnecessary file descriptors in
// the child process.
 
class cPipe {
private:
  pid_t pid;
  FILE *f;
public:
  cPipe(void);
  ~cPipe();
  operator FILE* () { return f; }
  bool Open(const char *Command, const char *Mode);
  int Close(void);
  };
 
// cBackTrace can be used for debugging.
 
class cStringList;
class cString;
 
class cBackTrace {
public:
  static cString Demangle(char *s);
  static void BackTrace(cStringList &StringList, int Level = 0, bool Mangled = false);
  static void BackTrace(FILE *f = NULL, int Level = 0, bool Mangled = false);
  static cString GetCaller(int Level = 0, bool Mangled = false);
  };
 
// SystemExec() implements a 'system()' call that closes all unnecessary file
// descriptors in the child process.
// With Detached=true, calls command in background and in a separate session,
// with stdin connected to /dev/null.
 
int SystemExec(const char *Command, bool Detached = false);
 
#endif //__THREAD_H