deal better with acquiring the same URI multiple times

This is an unlikely event for indexes and co, but it can happen quiet
easily e.g. for changelogs where you want to get the changelogs for
multiple binary package(version)s which happen to all be built from a
single source.

The interesting part is that the Acquire system actually detected this
already and set the item requesting the URI again to StatDone - expect
that this is hardly sufficient: an Item must be Complete=true as well
to be considered truely done and that is only the tip of the ::Done
handling iceberg. So instead of this StatDone hack we allow QItems to be
owned by multiple items and notify all owners about everything now,
so that for the point of each item they got it downloaded just for them.

1 files changed, 36 insertions, 8 deletions

diff --git a/apt-pkg/acquire.h b/apt-pkg/acquire.h
index fc90624e1..02031dafd 100644
--- a/apt-pkg/acquire.h
+++ b/apt-pkg/acquire.h
@@ -68,9 +68,10 @@
 
 #include <apt-pkg/macros.h>
 #include <apt-pkg/weakptr.h>
+#include <apt-pkg/hashes.h>
 
-#include <vector>
 #include <string>
+#include <vector>
 
 #include <stddef.h>
 #include <sys/time.h>
@@ -390,13 +391,13 @@ class pkgAcquire
  */
 struct pkgAcquire::ItemDesc : public WeakPointable
 {
-   /** \brief The URI from which to download this item. */
+   /** \brief URI from which to download this item. */
    std::string URI;
-   /** brief A description of this item. */
+   /** \brief description of this item. */
    std::string Description;
-   /** brief A shorter description of this item. */
+   /** \brief shorter description of this item. */
    std::string ShortDesc;
-   /** brief The underlying item which is to be downloaded. */
+   /** \brief underlying item which is to be downloaded. */
    Item *Owner;
 };
 									/*}}}*/
@@ -419,13 +420,26 @@ class pkgAcquire::Queue
    protected:
 
    /** \brief A single item placed in this queue. */
-   struct QItem : pkgAcquire::ItemDesc
+   struct QItem : public WeakPointable
    {
       /** \brief The next item in the queue. */
       QItem *Next;
       /** \brief The worker associated with this item, if any. */
       pkgAcquire::Worker *Worker;
 
+      /** \brief The URI from which to download this item. */
+      std::string URI;
+      /** \brief A description of this item. */
+      std::string Description;
+      /** \brief A shorter description of this item. */
+      std::string ShortDesc;
+      /** \brief The underlying items interested in the download */
+      std::vector<Item*> Owners;
+      // both, backward compatibility and easy access as syncing is interal
+      Item * Owner;
+
+      typedef std::vector<Item*>::const_iterator owner_iterator;
+
       /** \brief Assign the ItemDesc portion of this QItem from
        *  another ItemDesc
        */
@@ -434,10 +448,24 @@ class pkgAcquire::Queue
 	 URI = I.URI;
 	 Description = I.Description;
 	 ShortDesc = I.ShortDesc;
+	 Owners.clear();
+	 Owners.push_back(I.Owner);
 	 Owner = I.Owner;
       };
+
+      /** @return the sum of all expected hashes by all owners */
+      HashStringList GetExpectedHashes() const;
+
+      /** @return smallest maximum size of all owners */
+      unsigned long long GetMaximumSize() const;
+
+      /** \brief get partial files in order */
+      void SyncDestinationFiles() const;
+
+      /** @return the custom headers to use for this item */
+      std::string Custom600Headers() const;
    };
-   
+
    /** \brief The name of this queue. */
    std::string Name;
 
@@ -590,7 +618,7 @@ class pkgAcquire::UriIterator
       }
    };
    
-   inline pkgAcquire::ItemDesc const *operator ->() const {return CurItem;};
+   inline pkgAcquire::Queue::QItem 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;};