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 The socket to send SCM_RIGHTS message through
 105     */
 106    int PrivSepSocketFd;
 107    int PrivSepSocketFdChild;
 108
 109    /** \brief Set to \b true if the worker is in a state in which it
 110     *  might generate data or command responses.
 111     *
 112     *  \todo Is this right?  It's a guess.
 113     */
 114    bool InReady;
 115
 116    /** \brief Set to \b true if the worker is in a state in which it
 117     *  is legal to send commands to it.
 118     *
 119     *  \todo Is this right?
 120     */
 121    bool OutReady;
 122
 123    /** If \b true, debugging output will be sent to std::clog. */
 124    bool Debug;
 125
 126    /** \brief The raw text values of messages received from the
 127     *  worker, in sequence.
 128     */
 129    std::vector<std::string> MessageQueue;
 130
 131    /** \brief Buffers pending writes to the subprocess.
 132     *
 133     *  \todo Wouldn't a std::dequeue be more appropriate?
 134     */
 135    std::string OutQueue;
 136
 137    /** \brief Common code for the constructor.
 138     *
 139     *  Initializes NextQueue and NextAcquire to NULL; Process, InFd,
 140     *  and OutFd to -1, OutReady and InReady to \b false, and Debug
 141     *  from _config.
 142     */
 143    void Construct();
 144
 145    /** \brief Retrieve any available messages from the subprocess.
 146     *
 147     *  The messages are retrieved as in \link strutl.h ReadMessages()\endlink, and
 148     *  #MethodFailure() is invoked if an error occurs; in particular,
 149     *  if the pipe to the subprocess dies unexpectedly while a message
 150     *  is being read.
 151     *
 152     *  \return \b true if the messages were successfully read, \b
 153     *  false otherwise.
 154     */
 155    bool ReadMessages();
 156
 157    /** \brief Parse and dispatch pending messages.
 158     *
 159     *  This dispatches the message in a manner appropriate for its
 160     *  type.
 161     *
 162     *  \todo Several message types lack separate handlers.
 163     *
 164     *  \sa Capabilities(), SendConfiguration(), MediaChange()
 165     */
 166    bool RunMessages();
 167
 168    /** \brief Read and dispatch any pending messages from the
 169     *  subprocess.
 170     *
 171     *  \return \b false if the subprocess died unexpectedly while a
 172     *  message was being transmitted.
 173     */
 174    bool InFdReady();
 175
 176    /** \brief Send any pending commands to the subprocess.
 177     *
 178     *  This method will fail if there is no pending output.
 179     *
 180     *  \return \b true if all commands were succeeded, \b false if an
 181     *  error occurred (in which case MethodFailure() will be invoked).
 182     */
 183    bool OutFdReady();
 184
 185    /** \brief Handle a 100 Capabilities response from the subprocess.
 186     *
 187     *  \param Message the raw text of the message from the subprocess.
 188     *
 189     *  The message will be parsed and its contents used to fill
 190     *  #Config.  If #Config is NULL, this routine is a NOP.
 191     *
 192     *  \return \b true.
 193     */
 194    bool Capabilities(std::string Message);
 195
 196    /** \brief Send a 601 Configuration message (containing the APT
 197     *  configuration) to the subprocess.
 198     *
 199     *  The APT configuration will be send to the subprocess in a
 200     *  message of the following form:
 201     *
 202     *  <pre>
 203     *  601 Configuration
 204     *  Config-Item: Fully-Qualified-Item=Val
 205     *  Config-Item: Fully-Qualified-Item=Val
 206     *  ...
 207     *  </pre>
 208     *
 209     *  \return \b true if the command was successfully sent, \b false
 210     *  otherwise.
 211     */
 212    bool SendConfiguration();
 213
 214    /** \brief Handle a 403 Media Change message.
 215     *
 216     *  \param Message the raw text of the message; the Media field
 217     *  indicates what type of media should be changed, and the Drive
 218     *  field indicates where the media is located.
 219     *
 220     *  Invokes pkgAcquireStatus::MediaChange(Media, Drive) to ask the
 221     *  user to swap disks; informs the subprocess of the result (via
 222     *  603 Media Changed, with the Failed field set to \b true if the
 223     *  user cancelled the media change).
 224     */
 225    bool MediaChange(std::string Message);
 226
 227    /** \brief Invoked when the worked process dies unexpectedly.
 228     *
 229     *  Waits for the subprocess to terminate and generates an error if
 230     *  it terminated abnormally, then closes and blanks out all file
 231     *  descriptors.  Discards all pending messages from the
 232     *  subprocess.
 233     *
 234     *  \return \b false.
 235     */
 236    bool MethodFailure();
 237
 238    /** \brief Invoked when a fetch job is completed, either
 239     *  successfully or unsuccessfully.
 240     *
 241     *  Resets the status information for the worker process.
 242     */
 243    void ItemDone();
 244
 245    public:
 246
 247    /** \brief The queue entry that is currently being downloaded. */
 248    pkgAcquire::Queue::QItem *CurrentItem;
 249
 250    /** \brief The most recent status string received from the
 251     *  subprocess.
 252     */
 253    std::string Status;
 254
 255    /** \brief How many bytes of the file have been downloaded.  Zero
 256     *  if the current progress of the file cannot be determined.
 257     */
 258    unsigned long long CurrentSize;
 259
 260    /** \brief The total number of bytes to be downloaded.  Zero if the
 261     *  total size of the final is unknown.
 262     */
 263    unsigned long long TotalSize;
 264
 265    /** \brief How much of the file was already downloaded prior to
 266     *  starting this worker.
 267     */
 268    unsigned long long ResumePoint;
 269
 270    /** \brief Tell the subprocess to download the given item.
 271     *
 272     *  \param Item the item to queue up.
 273     *  \return \b true if the item was successfully enqueued.
 274     *
 275     *  Queues up a 600 URI Acquire message for the given item to be
 276     *  sent at the next possible moment.  Does \e not flush the output
 277     *  queue.
 278     */
 279    bool QueueItem(pkgAcquire::Queue::QItem *Item);
 280
 281    /** \brief Start up the worker and fill in #Config.
 282     *
 283     *  Reads the first message from the worker, which is assumed to be
 284     *  a 100 Capabilities message.
 285     *
 286     *  \return \b true if all operations completed successfully.
 287     */
 288    bool Start();
 289
 290    /** \brief Update the worker statistics (CurrentSize, TotalSize,
 291     *  etc).
 292     */
 293    void Pulse();
 294
 295    /** \return The fetch method configuration. */
 296    inline const MethodConfig *GetConf() const {return Config;};
 297
 298    /** \brief Create a new Worker to download files.
 299     *
 300     *  \param OwnerQ The queue into which this worker should be
 301     *  placed.
 302     *
 303     *  \param Config A location in which to store information about
 304     *  the fetch method.
 305     *
 306     *  \param Log The download progress indicator that should be used
 307     *  to report the progress of this worker.
 308     */
 309    Worker(Queue *OwnerQ,MethodConfig *Config,pkgAcquireStatus *Log);
 310
 311    /** \brief Create a new Worker that should just retrieve
 312     *  information about the fetch method.
 313     *
 314     *  Nothing in particular forces you to refrain from actually
 315     *  downloading stuff, but the various status callbacks won't be
 316     *  invoked.
 317     *
 318     *  \param Config A location in which to store information about
 319     *  the fetch method.
 320     */
 321    Worker(MethodConfig *Config);
 322
 323    /** \brief Clean up this worker.
 324     *
 325     *  Closes the file descriptors; if MethodConfig::NeedsCleanup is
 326     *  \b false, also rudely interrupts the worker with a SIGINT.
 327     */
 328    virtual ~Worker();
 329 };
 330
 331 /** @} */
 332
 333 #endif