apt-pkg/acquire-worker.h

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: acquire-worker.h,v 1.12 2001/02/20 07:03:17 jgg Exp $
   4 /* ######################################################################
   5
   6    Acquire Worker - Worker process manager
   7
   8    Each worker class is associated with exaclty one subprocess.
   9
  10    ##################################################################### */
  11                                                                         /*}}}*/
  12
  13 /** \addtogroup acquire
  14  *  @{
  15  *
  16  *  \file acquire-worker.h
  17  */
  18
  19 #ifndef PKGLIB_ACQUIRE_WORKER_H
  20 #define PKGLIB_ACQUIRE_WORKER_H
  21
  22 #include <apt-pkg/acquire.h>
  23 #include <apt-pkg/weakptr.h>
  24
  25 #include <sys/types.h>
  26 #include <string>
  27 #include <vector>
  28
  29 /** \brief A fetch subprocess.
  30  *
  31  *  A worker process is responsible for one stage of the fetch.  This
  32  *  class encapsulates the communications protocol between the master
  33  *  process and the worker, from the master end.
  34  *
  35  *  Each worker is intrinsically placed on two linked lists.  The
  36  *  Queue list (maintained in the #NextQueue variable) is maintained
  37  *  by the pkgAcquire::Queue class; it represents the set of workers
  38  *  assigned to a particular queue.  The Acquire list (maintained in
  39  *  the #NextAcquire variable) is maintained by the pkgAcquire class;
  40  *  it represents the set of active workers for a particular
  41  *  pkgAcquire object.
  42  *
  43  *  \todo Like everything else in the Acquire system, this has way too
  44  *  many protected items.
  45  *
  46  *  \sa pkgAcqMethod, pkgAcquire::Item, pkgAcquire
  47  */
  48 class pkgAcquire::Worker : public WeakPointable
  49 {
  50    /** \brief dpointer placeholder (for later in case we need it) */
  51    void *d;
  52
  53    friend class pkgAcquire;
  54
  55    protected:
  56    friend class Queue;
  57
  58    /** \brief The next link on the Queue list.
  59     *
  60     *  \todo This is always NULL; is it just for future use?
  61     */
  62    Worker *NextQueue;
  63
  64    /** \brief The next link on the Acquire list. */
  65    Worker *NextAcquire;
  66
  67    /** \brief The Queue with which this worker is associated. */
  68    Queue *OwnerQ;
  69
  70    /** \brief The download progress indicator to which progress
  71     *  messages should be sent.
  72     */
  73    pkgAcquireStatus *Log;
  74
  75    /** \brief The configuration of this method.  On startup, the
  76     *  target of this pointer is filled in with basic data about the
  77     *  method, as reported by the worker.
  78     */
  79    MethodConfig *Config;
  80
  81    /** \brief The access method to be used by this worker.
  82     *
  83     *  \todo Doesn't this duplicate Config->Access?
  84     */
  85    std::string Access;
  86
  87    /** \brief The PID of the subprocess. */
  88    pid_t Process;
  89
  90    /** \brief A file descriptor connected to the standard output of
  91     *  the subprocess.
  92     *
  93     *  Used to read messages and data from the subprocess.
  94     */
  95    int InFd;
  96
  97    /** \brief A file descriptor connected to the standard input of the
  98     *  subprocess.
  99     *
 100     *  Used to send commands and configuration data to the subprocess.
 101     */
 102    int OutFd;
 103
 104    /** \brief Set to \b true if the worker is in a state in which it
 105     *  might generate data or command responses.
 106     *
 107     *  \todo Is this right?  It's a guess.
 108     */
 109    bool InReady;
 110
 111    /** \brief Set to \b true if the worker is in a state in which it
 112     *  is legal to send commands to it.
 113     *
 114     *  \todo Is this right?
 115     */
 116    bool OutReady;
 117
 118    /** If \b true, debugging output will be sent to std::clog. */
 119    bool Debug;
 120
 121    /** \brief The raw text values of messages received from the
 122     *  worker, in sequence.
 123     */
 124    std::vector<std::string> MessageQueue;
 125
 126    /** \brief Buffers pending writes to the subprocess.
 127     *
 128     *  \todo Wouldn't a std::dequeue be more appropriate?
 129     */
 130    std::string OutQueue;
 131
 132    /** \brief Common code for the constructor.
 133     *
 134     *  Initializes NextQueue and NextAcquire to NULL; Process, InFd,
 135     *  and OutFd to -1, OutReady and InReady to \b false, and Debug
 136     *  from _config.
 137     */
 138    void Construct();
 139
 140    /** \brief Retrieve any available messages from the subprocess.
 141     *
 142     *  The messages are retrieved as in \link strutl.h ReadMessages()\endlink, and
 143     *  #MethodFailure() is invoked if an error occurs; in particular,
 144     *  if the pipe to the subprocess dies unexpectedly while a message
 145     *  is being read.
 146     *
 147     *  \return \b true if the messages were successfully read, \b
 148     *  false otherwise.
 149     */
 150    bool ReadMessages();
 151
 152    /** \brief Parse and dispatch pending messages.
 153     *
 154     *  This dispatches the message in a manner appropriate for its
 155     *  type.
 156     *
 157     *  \todo Several message types lack separate handlers.
 158     *
 159     *  \sa Capabilities(), SendConfiguration(), MediaChange()
 160     */
 161    bool RunMessages();
 162
 163    /** \brief Read and dispatch any pending messages from the
 164     *  subprocess.
 165     *
 166     *  \return \b false if the subprocess died unexpectedly while a
 167     *  message was being transmitted.
 168     */
 169    bool InFdReady();
 170
 171    /** \brief Send any pending commands to the subprocess.
 172     *
 173     *  This method will fail if there is no pending output.
 174     *
 175     *  \return \b true if all commands were succeeded, \b false if an
 176     *  error occurred (in which case MethodFailure() will be invoked).
 177     */
 178    bool OutFdReady();
 179
 180    /** \brief Handle a 100 Capabilities response from the subprocess.
 181     *
 182     *  \param Message the raw text of the message from the subprocess.
 183     *
 184     *  The message will be parsed and its contents used to fill
 185     *  #Config.  If #Config is NULL, this routine is a NOP.
 186     *
 187     *  \return \b true.
 188     */
 189    bool Capabilities(std::string Message);
 190
 191    /** \brief Send a 601 Configuration message (containing the APT
 192     *  configuration) to the subprocess.
 193     *
 194     *  The APT configuration will be send to the subprocess in a
 195     *  message of the following form:
 196     *
 197     *  <pre>
 198     *  601 Configuration
 199     *  Config-Item: Fully-Qualified-Item=Val
 200     *  Config-Item: Fully-Qualified-Item=Val
 201     *  ...
 202     *  </pre>
 203     *
 204     *  \return \b true if the command was successfully sent, \b false
 205     *  otherwise.
 206     */
 207    bool SendConfiguration();
 208
 209    /** \brief Handle a 403 Media Change message.
 210     *
 211     *  \param Message the raw text of the message; the Media field
 212     *  indicates what type of media should be changed, and the Drive
 213     *  field indicates where the media is located.
 214     *
 215     *  Invokes pkgAcquireStatus::MediaChange(Media, Drive) to ask the
 216     *  user to swap disks; informs the subprocess of the result (via
 217     *  603 Media Changed, with the Failed field set to \b true if the
 218     *  user cancelled the media change).
 219     */
 220    bool MediaChange(std::string Message);
 221
 222    /** \brief Invoked when the worked process dies unexpectedly.
 223     *
 224     *  Waits for the subprocess to terminate and generates an error if
 225     *  it terminated abnormally, then closes and blanks out all file
 226     *  descriptors.  Discards all pending messages from the
 227     *  subprocess.
 228     *
 229     *  \return \b false.
 230     */
 231    bool MethodFailure();
 232
 233    /** \brief Invoked when a fetch job is completed, either
 234     *  successfully or unsuccessfully.
 235     *
 236     *  Resets the status information for the worker process.
 237     */
 238    void ItemDone();
 239
 240    public:
 241
 242    /** \brief The queue entry that is currently being downloaded. */
 243    pkgAcquire::Queue::QItem *CurrentItem;
 244
 245    /** \brief The most recent status string received from the
 246     *  subprocess.
 247     */
 248    std::string Status;
 249
 250    /** \brief How many bytes of the file have been downloaded.  Zero
 251     *  if the current progress of the file cannot be determined.
 252     */
 253    unsigned long long CurrentSize;
 254
 255    /** \brief The total number of bytes to be downloaded.  Zero if the
 256     *  total size of the final is unknown.
 257     */
 258    unsigned long long TotalSize;
 259
 260    /** \brief How much of the file was already downloaded prior to
 261     *  starting this worker.
 262     */
 263    unsigned long long ResumePoint;
 264
 265    /** \brief Tell the subprocess to download the given item.
 266     *
 267     *  \param Item the item to queue up.
 268     *  \return \b true if the item was successfully enqueued.
 269     *
 270     *  Queues up a 600 URI Acquire message for the given item to be
 271     *  sent at the next possible moment.  Does \e not flush the output
 272     *  queue.
 273     */
 274    bool QueueItem(pkgAcquire::Queue::QItem *Item);
 275
 276    /** \brief Start up the worker and fill in #Config.
 277     *
 278     *  Reads the first message from the worker, which is assumed to be
 279     *  a 100 Capabilities message.
 280     *
 281     *  \return \b true if all operations completed successfully.
 282     */
 283    bool Start();
 284
 285    /** \brief Update the worker statistics (CurrentSize, TotalSize,
 286     *  etc).
 287     */
 288    void Pulse();
 289
 290    /** \return The fetch method configuration. */
 291    inline const MethodConfig *GetConf() const {return Config;};
 292
 293    /** \brief Create a new Worker to download files.
 294     *
 295     *  \param OwnerQ The queue into which this worker should be
 296     *  placed.
 297     *
 298     *  \param Config A location in which to store information about
 299     *  the fetch method.
 300     *
 301     *  \param Log The download progress indicator that should be used
 302     *  to report the progress of this worker.
 303     */
 304    Worker(Queue *OwnerQ,MethodConfig *Config,pkgAcquireStatus *Log);
 305
 306    /** \brief Create a new Worker that should just retrieve
 307     *  information about the fetch method.
 308     *
 309     *  Nothing in particular forces you to refrain from actually
 310     *  downloading stuff, but the various status callbacks won't be
 311     *  invoked.
 312     *
 313     *  \param Config A location in which to store information about
 314     *  the fetch method.
 315     */
 316    Worker(MethodConfig *Config);
 317
 318    /** \brief Clean up this worker.
 319     *
 320     *  Closes the file descriptors; if MethodConfig::NeedsCleanup is
 321     *  \b false, also rudely interrupts the worker with a SIGINT.
 322     */
 323    virtual ~Worker();
 324 };
 325
 326 /** @} */
 327
 328 #endif