Thttpd source code parsing timer Module

Thttpd source code parsing timer Module

• Thttpd is a lightweight HTTP server with a executable file of only 50 kb. The first in the nametTiny, Turbo, or throttling
• Compared with Lighttpd, memcached, and redis, they are very small, with less than 8 K rows, and the last three are respectively 60 K, 13 K, and 86 K.
• Supports HTTP/1.1 and CGI; implements Io multiplexing, single-thread, and portable; implements the URL-based file traffic Limit Function
• It is particularly suitable for scenarios where a large number of Static Data Accesses exist.
• Maintenance has been stopped on April 9, 2004. There is a bug about X-forwarded-for HTTP header. Later, stthhpd was developed based on this project.
• Performance Comparison
• This article analyzes the timer Module

Timer Module

• Includes two files: timer. h and timer. C.
• Globally open hash is used. The default size is 67. Values on each hash node are arranged in chronological order.
• Clientdata is defined as follows:

  typedef union {  void* p;  int i;  long l;  } ClientData;

• The timerproc type declaration is as follows:void TimerProc( ClientData client_data, struct timeval* nowP ). The function will be called when the timer times out.
• The timer structure is defined as follows:

  typedef struct TimerStruct {  TimerProc* timer_proc;  ClientData client_data;  long msecs;  int periodic;  struct timeval time;  struct TimerStruct* prev;  struct TimerStruct* next;  int hash;  } Timer;

• void tmr_init( void )
  • Initialize the timer package, that is, the timer hash table.
• Timer* tmr_create( struct timeval* nowP, TimerProc* timer_proc, ClientData client_data, long msecs, int periodic )
  • Create a timer, which is a one-time/periodic task. Add the timer to the hash table.
  • The timer time is set to the nowp time plus msecs milliseconds. If nowp is set to 0, it is set to the current time plus msecs milliseconds.
• timeval* tmr_timeout( struct timeval* nowP )
  • Returns the interval from the next trigger.
  • Call tmr_mstimeout to obtain
• tmr_mstimeout( struct timeval* nowP )
  • Returns the number of milliseconds from the next trigger interval, that is, the number of milliseconds from nowp, after which a timer is triggered in the hash table.
  • Because each linked list in the hash table is ordered, just traverse the hash table once.
• void tmr_run( struct timeval* nowP )
  • Traverse the hash table. If the timer does not time out, call timer_proc.
  • If the timer is periodic, msecs is extended after the call time. If the timer is non-cyclical, tmr_cancel is called to remove
• void tmr_reset( struct timeval* nowP, Timer* timer )
  • Run the timer again, and set the clock to the current time nowp plus the timer duration.
• void tmr_cancel( Timer* timer )
  • Release the timer. Because tmr_cancel has been called for all non-periodic timers in tmr_run, you no longer need to call the non-periodic timer.
  • Adding timers to the free_timers linked list saves free and malloc overhead, which is equivalent to a buffer pool.
• void tmr_cleanup( void )
  • Clear the timer package and release all useless memory: free_timers linked list
• void tmr_destroy( void )
  • Call tmr_cancel to release all timers to prepare for exit,
• void tmr_logstats( long secs )
  • Generate debugging log information and record the number of currently allocated, in-use, and free timers
• Operate static functions of a hash table
  • Hash:(time.tv_sec ^ time.tv_usec) % 67Obtain the hash value.
  • Rochelle Add: Insert a timer
  • Rochelle remove: removes a timer.
  • Re_sort: the timer struct contains the previous hash value. If the timer value changes, remove it and re-calculate the hash value and insert it to the correct position.

Use of timer Module

• Use timer-like modules in the main function
• Call tmr_init for initialization
• Create a periodic timer with a period of occasional_time. The callback function is occasional.
• Create a timer with a cycle of 5 seconds and the callback function is idle.
• Creates a periodic timer with a cycle of throttle_time and calls back update_throttles.
• Creates a periodic timer with a period of stats_time and calls back show_stats.
• In the main event processing cycle:
  • If no socket event occurs, call tmr_run and continue once.
  • If a new connection exists, continue to ensure that the new connection takes priority.
  • If an event occurs, the event is processed.
  • Run tmr_run once
• Occasional
  • Call mmc_cleanup
  • Call tmr_cleanup to clear useless timer Memory Pool
  • Set watchdog_flag = 1 so that watchdog knows that the program is still running.
• Idle
• Update_throttles update traffic control
• Show_stats
  • Call the logstats function to record information.

　　
　　

For more information, see focustc. The blog address is http://blog.csdn.net/caozhk.