diff options
Diffstat (limited to 'apt-pkg/acquire.h')
| -rw-r--r-- | apt-pkg/acquire.h | 541 |
1 files changed, 512 insertions, 29 deletions
diff --git a/apt-pkg/acquire.h b/apt-pkg/acquire.h index 27bb3d363..64dafdc9d 100644 --- a/apt-pkg/acquire.h +++ b/apt-pkg/acquire.h @@ -29,6 +29,40 @@ ##################################################################### */ /*}}}*/ + +/** \defgroup acquire Acquire system + * + * \brief The Acquire system is responsible for retrieving files from + * local or remote URIs and postprocessing them (for instance, + * verifying their authenticity). The core class in this system is + * pkgAcquire, which is responsible for managing the download queues + * during the download. There is at least one download queue for + * each supported protocol; protocols such as http may provide one + * queue per host. + * + * Each file to download is represented by a subclass of + * pkgAcquire::Item. The files add themselves to the download + * queue(s) by providing their URI information to + * pkgAcquire::Item::QueueURI, which calls pkgAcquire::Enqueue. + * + * Once the system is set up, the Run method will spawn subprocesses + * to handle the enqueued URIs; the scheduler will then take items + * from the queues and feed them into the handlers until the queues + * are empty. + * + * \todo Acquire supports inserting an object into several queues at + * once, but it is not clear what its behavior in this case is, and + * no subclass of pkgAcquire::Item seems to actually use this + * capability. + */ + +/** \addtogroup acquire + * + * @{ + * + * \file acquire.h + */ + #ifndef PKGLIB_ACQUIRE_H #define PKGLIB_ACQUIRE_H @@ -46,6 +80,15 @@ using std::string; #include <unistd.h> class pkgAcquireStatus; + +/** \brief The core download scheduler. + * + * This class represents an ongoing download. It manages the lists + * of active and pending downloads and handles setting up and tearing + * down download-related structures. + * + * \todo Why all the protected data items and methods? + */ class pkgAcquire { public: @@ -60,97 +103,299 @@ class pkgAcquire typedef vector<Item *>::iterator ItemIterator; typedef vector<Item *>::const_iterator ItemCIterator; - + protected: - // List of items to fetch + /** \brief A list of items to download. + * + * This is built monotonically as items are created and only + * emptied when the download shuts down. + */ vector<Item *> Items; - // List of active queues and fetched method configuration parameters + /** \brief The head of the list of active queues. + * + * \todo why a hand-managed list of queues instead of std::list or + * std::set? + */ Queue *Queues; + + /** \brief The head of the list of active workers. + * + * \todo why a hand-managed list of workers instead of std::list + * or std::set? + */ Worker *Workers; + + /** \brief The head of the list of acquire method configurations. + * + * Each protocol (http, ftp, gzip, etc) via which files can be + * fetched can have a representation in this list. The + * configuration data is filled in by parsing the 100 Capabilities + * string output by a method on startup (see + * pkgAcqMethod::pkgAcqMethod and pkgAcquire::GetConfig). + * + * \todo why a hand-managed config dictionary instead of std::map? + */ MethodConfig *Configs; + + /** \brief The progress indicator for this download. */ pkgAcquireStatus *Log; + + /** \brief The total size of the files which are to be fetched. + * + * This is not necessarily the total number of bytes to download + * when, e.g., download resumption and list updates via patches + * are taken into account. + */ unsigned long ToFetch; - // Configurable parameters for the schedular - enum {QueueHost,QueueAccess} QueueMode; + // Configurable parameters for the scheduler + + /** \brief Represents the queuing strategy for remote URIs. */ + enum QueueStrategy { + /** \brief Generate one queue for each protocol/host combination; downloads from + * multiple hosts can proceed in parallel. + */ + QueueHost, + /** \brief Generate a single queue for each protocol; serialize + * downloads from multiple hosts. + */ + QueueAccess} QueueMode; + + /** \brief If \b true, debugging information will be dumped to std::clog. */ bool Debug; + /** \brief If \b true, a download is currently in progress. */ bool Running; - + + /** \brief Add the given item to the list of items. */ void Add(Item *Item); + + /** \brief Remove the given item from the list of items. */ void Remove(Item *Item); + + /** \brief Add the given worker to the list of workers. */ void Add(Worker *Work); + + /** \brief Remove the given worker from the list of workers. */ void Remove(Worker *Work); + /** \brief Insert the given fetch request into the appropriate queue. + * + * \param Item The URI to download and the item to download it + * for. Copied by value into the queue; no reference to Item is + * retained. + */ void Enqueue(ItemDesc &Item); + + /** \brief Remove all fetch requests for this item from all queues. */ void Dequeue(Item *Item); + + /** \brief Determine the fetch method and queue of a URI. + * + * \param URI The URI to fetch. + * + * \param[out] Config A location in which to place the method via + * which the URI is to be fetched. + * + * \return the string-name of the queue in which a fetch request + * for the given URI should be placed. + */ string QueueName(string URI,MethodConfig const *&Config); - // FDSET managers for derived classes + /** \brief Build up the set of file descriptors upon which select() should + * block. + * + * The default implementation inserts the file descriptors + * corresponding to active downloads. + * + * \param[out] Fd The largest file descriptor in the generated sets. + * + * \param[out] RSet The set of file descriptors that should be + * watched for input. + * + * \param[out] WSet The set of file descriptors that should be + * watched for output. + */ virtual void SetFds(int &Fd,fd_set *RSet,fd_set *WSet); + + /** Handle input from and output to file descriptors which select() + * has determined are ready. The default implementation + * dispatches to all active downloads. + * + * \param RSet The set of file descriptors that are ready for + * input. + * + * \param WSet The set of file descriptors that are ready for + * output. + */ virtual void RunFds(fd_set *RSet,fd_set *WSet); - // A queue calls this when it dequeues an item + /** \brief Check for idle queues with ready-to-fetch items. + * + * Called by pkgAcquire::Queue::Done each time an item is dequeued + * but remains on some queues; i.e., another queue should start + * fetching it. + */ void Bump(); public: + /** \brief Retrieve information about a fetch method by name. + * + * \param Access The name of the method to look up. + * + * \return the method whose name is Access, or \b NULL if no such method exists. + */ MethodConfig *GetConfig(string Access); - enum RunResult {Continue,Failed,Cancelled}; + /** \brief Provides information on how a download terminated. */ + enum RunResult { + /** \brief All files were fetched successfully. */ + Continue, + + /** \brief Some files failed to download. */ + Failed, + + /** \brief The download was cancelled by the user (i.e., #Log's + * pkgAcquireStatus::Pulse() method returned \b false). + */ + Cancelled}; - RunResult Run(int PulseIntervall=500000); + /** \brief Download all the items that have been Add()ed to this + * download process. + * + * This method will block until the download completes, invoking + * methods on #Log to report on the progress of the download. + * + * \param PulseInterval The method pkgAcquireStatus::Pulse will be + * invoked on #Log at intervals of PulseInterval milliseconds. + * + * \return the result of the download. + */ + RunResult Run(int PulseInterval=500000); + + /** \brief Remove all items from this download process, terminate + * all download workers, and empty all queues. + */ void Shutdown(); - // Simple iteration mechanism + /** \brief Get the first #Worker object. + * + * \return the first active worker in this download process. + */ inline Worker *WorkersBegin() {return Workers;}; + + /** \brief Advance to the next #Worker object. + * + * \return the worker immediately following I, or \b NULL if none + * exists. + */ Worker *WorkerStep(Worker *I); + + /** \brief Get the head of the list of items. */ inline ItemIterator ItemsBegin() {return Items.begin();}; + + /** \brief Get the end iterator of the list of items. */ inline ItemIterator ItemsEnd() {return Items.end();}; // Iterate over queued Item URIs class UriIterator; + /** \brief Get the head of the list of enqueued item URIs. + * + * This iterator will step over every element of every active + * queue. + */ UriIterator UriBegin(); + /** \brief Get the end iterator of the list of enqueued item URIs. */ UriIterator UriEnd(); - // Cleans out the download dir + /** Deletes each entry in the given directory that is not being + * downloaded by this object. For instance, when downloading new + * list files, calling Clean() will delete the old ones. + * + * \param Dir The directory to be cleaned out. + * + * \return \b true if the directory exists and is readable. + */ bool Clean(string Dir); - // Returns the size of the total download set + /** \return the total size in bytes of all the items included in + * this download. + */ double TotalNeeded(); + + /** \return the size in bytes of all non-local items included in + * this download. + */ double FetchNeeded(); + + /** \return the amount of data to be fetched that is already + * present on the filesystem. + */ double PartialPresent(); + /** \brief Construct a new pkgAcquire. + * + * \param Log The progress indicator associated with this + * download, or \b NULL for none. This object is not owned by the + * download process and will not be deleted when the pkgAcquire + * object is destroyed. Naturally, it should live for at least as + * long as the pkgAcquire object does. + */ pkgAcquire(pkgAcquireStatus *Log = 0); + + /** \brief Destroy this pkgAcquire object. + * + * Destroys all queue, method, and item objects associated with + * this download. + */ virtual ~pkgAcquire(); }; -// Description of an Item+URI +/** \brief Represents a single download source from which an item + * should be downloaded. + * + * An item may have several assocated ItemDescs over its lifetime. + */ struct pkgAcquire::ItemDesc { + /** \brief The URI from which to download this item. */ string URI; + /** brief A description of this item. */ string Description; + /** brief A shorter description of this item. */ string ShortDesc; + /** brief The underlying item which is to be downloaded. */ Item *Owner; }; -// List of possible items queued for download. +/** \brief A single download queue in a pkgAcquire object. + * + * \todo Why so many protected values? + */ class pkgAcquire::Queue { friend class pkgAcquire; friend class pkgAcquire::UriIterator; friend class pkgAcquire::Worker; + + /** \brief The next queue in the pkgAcquire object's list of queues. */ Queue *Next; protected: - // Queued item + /** \brief A single item placed in this queue. */ struct QItem : pkgAcquire::ItemDesc { - QItem *Next; + /** \brief The next item in the queue. */ + QItem *Next; + /** \brief The worker associated with this item, if any. */ pkgAcquire::Worker *Worker; - + + /** \brief Assign the ItemDesc portion of this QItem from + * another ItemDesc + */ void operator =(pkgAcquire::ItemDesc const &I) { URI = I.URI; @@ -160,45 +405,141 @@ class pkgAcquire::Queue }; }; - // Name of the queue + /** \brief The name of this queue. */ string Name; - // Items queued into this queue + /** \brief The head of the list of items contained in this queue. + * + * \todo why a by-hand list instead of an STL structure? + */ QItem *Items; + + /** \brief The head of the list of workers associated with this queue. + * + * \todo This is plural because support exists in Queue for + * multiple workers. However, it does not appear that there is + * any way to actually associate more than one worker with a + * queue. + * + * \todo Why not just use a std::set? + */ pkgAcquire::Worker *Workers; + + /** \brief the download scheduler with which this queue is associated. */ pkgAcquire *Owner; + + /** \brief The number of entries in this queue that are currently + * being downloaded. + */ signed long PipeDepth; + + /** \brief The maximum number of entries that this queue will + * attempt to download at once. + */ unsigned long MaxPipeDepth; public: - // Put an item into this queue + /** \brief Insert the given fetch request into this queue. */ void Enqueue(ItemDesc &Item); + + /** \brief Remove all fetch requests for the given item from this queue. + * + * \return \b true if at least one request was removed from the queue. + */ bool Dequeue(Item *Owner); - // Find a Queued item + /** \brief Locate an item in this queue. + * + * \param URI A URI to match against. + * \param Owner A pkgAcquire::Worker to match against. + * + * \return the first item in the queue whose URI is #URI and that + * is being downloaded by #Owner. + */ QItem *FindItem(string URI,pkgAcquire::Worker *Owner); + + /** Presumably this should start downloading an item? + * + * \todo Unimplemented. Implement it or remove? + */ bool ItemStart(QItem *Itm,unsigned long Size); + + /** \brief Remove the given item from this queue and set its state + * to pkgAcquire::Item::StatDone. + * + * If this is the only queue containing the item, the item is also + * removed from the main queue by calling pkgAcquire::Dequeue. + * + * \param Itm The item to remove. + * + * \return \b true if no errors are encountered. + */ bool ItemDone(QItem *Itm); + /** \brief Start the worker process associated with this queue. + * + * If a worker process is already associated with this queue, + * this is equivalent to calling Cycle(). + * + * \return \b true if the startup was successful. + */ bool Startup(); + + /** \brief Shut down the worker process associated with this queue. + * + * \param Final If \b true, then the process is stopped unconditionally. + * Otherwise, it is only stopped if it does not need cleanup + * as indicated by the pkgAcqMethod::NeedsCleanup member of + * its configuration. + * + * \return \b true. + */ bool Shutdown(bool Final); + + /** \brief Send idle items to the worker process. + * + * Fills up the pipeline by inserting idle items into the worker's queue. + */ bool Cycle(); + + /** \brief Check for items that could be enqueued. + * + * Call this after an item placed in multiple queues has gone from + * the pkgAcquire::Item::StatFetching state to the + * pkgAcquire::Item::StatIdle state, to possibly refill an empty queue. + * This is an alias for Cycle(). + * + * \todo Why both this and Cycle()? Are they expected to be + * different someday? + */ void Bump(); + /** \brief Create a new Queue. + * + * \param Name The name of the new queue. + * \param Owner The download process that owns the new queue. + */ Queue(string Name,pkgAcquire *Owner); + + /** Shut down all the worker processes associated with this queue + * and empty the queue. + */ ~Queue(); }; +/** \brief Iterates over all the URIs being fetched by a pkgAcquire object. */ class pkgAcquire::UriIterator { + /** The next queue to iterate over. */ pkgAcquire::Queue *CurQ; + /** The item that we currently point at. */ pkgAcquire::Queue::QItem *CurItem; public: - // Advance to the next item inline void operator ++() {operator ++();}; + void operator ++(int) { CurItem = CurItem->Next; @@ -209,11 +550,14 @@ class pkgAcquire::UriIterator } }; - // Accessors inline pkgAcquire::ItemDesc const *operator ->() const {return CurItem;}; inline bool operator !=(UriIterator const &rhs) const {return rhs.CurQ != CurQ || rhs.CurItem != CurItem;}; inline bool operator ==(UriIterator const &rhs) const {return rhs.CurQ == CurQ && rhs.CurItem == CurItem;}; + /** \brief Create a new UriIterator. + * + * \param Q The queue over which this UriIterator should iterate. + */ UriIterator(pkgAcquire::Queue *Q) : CurQ(Q), CurItem(0) { while (CurItem == 0 && CurQ != 0) @@ -224,61 +568,200 @@ class pkgAcquire::UriIterator } }; -// Configuration information from each method +/** \brief Information about the properties of a single acquire method. */ struct pkgAcquire::MethodConfig { + /** \brief The next link on the acquire method list. + * + * \todo Why not an STL container? + */ MethodConfig *Next; + /** \brief The name of this acquire method (e.g., http). */ string Access; + /** \brief The implementation version of this acquire method. */ string Version; + + /** \brief If \b true, only one download queue should be created for this + * method. + */ bool SingleInstance; + + /** \brief If \b true, this method supports pipelined downloading. */ bool Pipeline; + + /** \brief If \b true, the worker process should send the entire + * APT configuration tree to the fetch subprocess when it starts + * up. + */ bool SendConfig; + + /** \brief If \b true, this fetch method does not require network access; + * all files are to be acquired from the local disk. + */ bool LocalOnly; + + /** \brief If \b true, the subprocess has to carry out some cleanup + * actions before shutting down. + * + * For instance, the cdrom method needs to unmount the CD after it + * finishes. + */ bool NeedsCleanup; + + /** \brief If \b true, this fetch method acquires files from removable media. */ bool Removable; + /** \brief Set up the default method parameters. + * + * All fields are initialized to NULL, "", or \b false as + * appropriate. + */ MethodConfig(); }; +/** \brief A monitor object for downloads controlled by the pkgAcquire class. + * + * \todo Why protected members? + * + * \todo Should the double members be uint64_t? + */ class pkgAcquireStatus { protected: + /** \brief The last time at which this monitor object was updated. */ struct timeval Time; + + /** \brief The time at which the download started. */ struct timeval StartTime; + + /** \brief The number of bytes fetched as of the previous call to + * pkgAcquireStatus::Pulse, including local items. + */ double LastBytes; + + /** \brief The current rate of download as of the most recent call + * to pkgAcquireStatus::Pulse, in bytes per second. + */ double CurrentCPS; + + /** \brief The number of bytes fetched as of the most recent call + * to pkgAcquireStatus::Pulse, including local items. + */ double CurrentBytes; + + /** \brief The total number of bytes that need to be fetched. + * + * \warning This member is inaccurate, as new items might be + * enqueued while the download is in progress! + */ double TotalBytes; + + /** \brief The total number of bytes accounted for by items that + * were successfully fetched. + */ double FetchedBytes; + + /** \brief The amount of time that has elapsed since the download + * started. + */ unsigned long ElapsedTime; + + /** \brief The total number of items that need to be fetched. + * + * \warning This member is inaccurate, as new items might be + * enqueued while the download is in progress! + */ unsigned long TotalItems; + + /** \brief The number of items that have been successfully downloaded. */ unsigned long CurrentItems; public: + /** \brief If \b true, the download scheduler should call Pulse() + * at the next available opportunity. + */ bool Update; + + /** \brief If \b true, extra Pulse() invocations will be performed. + * + * With this option set, Pulse() will be called every time that a + * download item starts downloading, finishes downloading, or + * terminates with an error. + */ bool MorePulses; - // Called by items when they have finished a real download + /** \brief Invoked when a local or remote file has been completely fetched. + * + * \param Size The size of the file fetched. + * + * \param ResumePoint How much of the file was already fetched. + */ virtual void Fetched(unsigned long Size,unsigned long ResumePoint); - // Called to change media + /** \brief Invoked when the user should be prompted to change the + * inserted removable media. + * + * This method should not return until the user has confirmed to + * the user interface that the media change is complete. + * + * \param Media The name of the media type that should be changed. + * + * \param Drive The identifying name of the drive whose media + * should be changed. + * + * \return \b true if the user confirms the media change, \b + * false if it is cancelled. + * + * \todo This is a horrible blocking monster; it should be CPSed + * with prejudice. + */ virtual bool MediaChange(string Media,string Drive) = 0; - // Each of these is called by the workers when an event occures + /** \brief Invoked when an item is confirmed to be up-to-date. + + * For instance, when an HTTP download is informed that the file on + * the server was not modified. + */ virtual void IMSHit(pkgAcquire::ItemDesc &/*Itm*/) {}; + + /** \brief Invoked when some of an item's data is fetched. */ virtual void Fetch(pkgAcquire::ItemDesc &/*Itm*/) {}; + + /** \brief Invoked when an item is successfully and completely fetched. */ virtual void Done(pkgAcquire::ItemDesc &/*Itm*/) {}; + + /** \brief Invoked when the process of fetching an item encounters + * a fatal error. + */ virtual void Fail(pkgAcquire::ItemDesc &/*Itm*/) {}; - virtual bool Pulse(pkgAcquire *Owner); // returns false on user cancel + + /** \brief Periodically invoked while the Acquire process is underway. + * + * Subclasses should first call pkgAcquireStatus::Pulse(), then + * update their status output. The download process is blocked + * while Pulse() is being called. + * + * \return \b false if the user asked to cancel the whole Acquire process. + * + * \see pkgAcquire::Run + */ + virtual bool Pulse(pkgAcquire *Owner); + + /** \brief Invoked when the Acquire process starts running. */ virtual void Start(); + + /** \brief Invoked when the Acquire process stops running. */ virtual void Stop(); + /** \brief Initialize all counters to 0 and the time to the current time. */ pkgAcquireStatus(); virtual ~pkgAcquireStatus() {}; }; +/** @} */ + #endif |