[pan2: 29/68] Reduce memory allocation for multiparts.

[Petr Kovář <pmkovar src gnome org>]

commit 514c3d39e4f3e39776f95159f75580c61d0d8f42
Author: K. Haley <haleykd users sf net>
Date:   Sat Jul 31 16:05:21 2010 -0600

    Reduce memory allocation for multiparts.

 pan/data/parts.cc |   58 ++++++++++++++++++++--------------------------------
 pan/data/parts.h  |   18 ++++++++--------
 2 files changed, 31 insertions(+), 45 deletions(-)
---
diff --git a/pan/data/parts.cc b/pan/data/parts.cc
index 41a7de5..11cfe71 100644
--- a/pan/data/parts.cc
+++ b/pan/data/parts.cc
@@ -131,7 +131,6 @@ namespace
 ***/
 
 Parts :: Parts ():
-  n_parts_found (0),
   n_parts_total (0),
   part_mid_buf_len (0),
   parts (0),
@@ -142,19 +141,17 @@ Parts :: Parts ():
 void
 Parts :: clear ()
 {
-  delete [] parts;
-  parts = 0;
+  part_v tmp;
+  parts.swap(tmp);
 
   delete [] part_mid_buf;
   part_mid_buf = 0;
 
   part_mid_buf_len = 0;
-  n_parts_found = 0;
   n_parts_total = 0;
 }
 
 Parts :: Parts (const Parts& that):
-  n_parts_found (0),
   n_parts_total (0),
   part_mid_buf_len (0),
   parts (0),
@@ -168,20 +165,14 @@ Parts :: operator= (const Parts& that)
 {
   clear ();
 
-  n_parts_found = that.n_parts_found;
   n_parts_total = that.n_parts_total;
   part_mid_buf_len = that.part_mid_buf_len;
+  parts.reserve( n_parts_total );
+  parts = that.parts;
+  assert( parts.capacity() == n_parts_total );
   part_mid_buf = new char [part_mid_buf_len];
   memcpy (part_mid_buf, that.part_mid_buf, part_mid_buf_len);
 
-  Part * part = parts = new Part [n_parts_found];
-  const Part * that_part = that.parts;
-  for (size_t i=0; i<n_parts_found; ++i, ++part, ++that_part) {
-    part->number = that_part->number;
-    part->bytes = that_part->bytes;
-    part->mid_offset = that_part->mid_offset;
-  }
-
   return *this;
 }
 
@@ -208,11 +199,11 @@ Parts :: get_part_info (number_t        part_number,
 {
   Part findme;
   findme.number = part_number;
-  Part * p = std::lower_bound (parts, parts+n_parts_found, findme);
-  if ((p == parts+n_parts_found) || (p->number != part_number))
+  part_v::const_iterator p = std::lower_bound (parts.begin(), parts.end(), findme);
+  if ((p == parts.end()) || (p->number != part_number))
     return false;
 
-  unpack_message_id (setme_message_id, p, reference_mid);
+  unpack_message_id (setme_message_id, &(*p), reference_mid);
   setme_byte_count = p->bytes;
   return true;
 }
@@ -226,17 +217,19 @@ Parts :: set_parts (const PartBatch& p)
 {
   clear ();
 
-  n_parts_found = p.n_parts_found;
+  unsigned int n_parts_found = p.n_parts_found;
   n_parts_total = p.n_parts_total;
   part_mid_buf_len = p.packed_mids_len;
+  parts.reserve(n_parts_total);
 
   char * pch = part_mid_buf = new char [part_mid_buf_len];
-  Part * part = parts = new Part [n_parts_found];
+  Part part;
   PartBatch::parts_t::const_iterator in = p.parts.begin();
-  for (size_t i=0, n=n_parts_found; i<n; ++i, ++in, ++part) {
-    part->number = in->number;
-    part->bytes = in->bytes;
-    part->mid_offset = pch - part_mid_buf;
+  for (size_t i=0; i<n_parts_found; ++i, ++in) {
+    part.number = in->number;
+    part.bytes = in->bytes;
+    part.mid_offset = pch - part_mid_buf;
+    parts.push_back(part);
     memcpy (pch, in->packed_mid, in->len_used);
     pch += in->len_used;
   }
@@ -252,21 +245,13 @@ Parts :: add_part (number_t            num,
 {
   Part findme;
   findme.number = num;
-  Part * p = std::lower_bound (parts, parts+n_parts_found, findme);
-  if (p!=parts+n_parts_found && p->number == num) // we have it already
+  part_v::iterator p = std::lower_bound (parts.begin(), parts.end(), findme);
+  if (p!=parts.end() && p->number == num) // we have it already
     return false;
 
-  const int insert_index = (p - parts);
-  Part * buf = new Part [n_parts_found+1];
-  std::copy (parts, parts+insert_index, buf);
-  std::copy (parts+insert_index, parts+n_parts_found, buf+insert_index+1);
-  delete [] parts;
-  parts = buf;
-  buf += insert_index;
-  buf->number = num;
-  buf->bytes = bytes;
-  buf->mid_offset = part_mid_buf_len;
-  ++n_parts_found;
+  findme.bytes = bytes;
+  findme.mid_offset = part_mid_buf_len;
+  parts.insert(p, findme);
 
   Packer packer;
   pack_message_id (packer, mid, reference_mid);
@@ -304,6 +289,7 @@ PartBatch :: init (const Quark  & mid,
   this->n_parts_found = 0; // they haven't been added yet
 
   parts.clear();
+  parts.reserve(n_parts_total);
 }
 
 void
diff --git a/pan/data/parts.h b/pan/data/parts.h
index b3f34fc..4057f2c 100644
--- a/pan/data/parts.h
+++ b/pan/data/parts.h
@@ -57,10 +57,10 @@ namespace pan
         bytes_t bytes;
         bool operator< (const Part& that) const { return number < that.number; }
       };
-      number_t n_parts_found;
       number_t n_parts_total;
       bytes_t part_mid_buf_len;
-      Part * parts;
+      typedef std::vector<Part> part_v;
+      part_v parts;
       char * part_mid_buf;
       void unpack_message_id (std::string  & setme,
                               const Part   * p,
@@ -72,7 +72,7 @@ namespace pan
           const Parts& parts;
           mutable std::string midbuf;
           int n;
-          const Part* get_part() const { return parts.parts + n; }
+          const Part& get_part() const { return parts.parts[n]; }
         public:
           const_iterator (const Quark& q,
                           const Parts& p,
@@ -84,10 +84,10 @@ namespace pan
           const_iterator& operator++() { ++n; return *this; }
           const_iterator operator++(int)
                              { const_iterator tmp=*this; ++*this; return tmp; }
-          bytes_t bytes() const { return get_part()->bytes; }
-          number_t number() const { return get_part()->number; }
+          bytes_t bytes() const { return get_part().bytes; }
+          number_t number() const { return get_part().number; }
           const std::string& mid() const {
-            parts.unpack_message_id (midbuf, get_part(), reference_mid);
+            parts.unpack_message_id (midbuf, &(get_part()), reference_mid);
             return midbuf;
           }
       };
@@ -95,7 +95,7 @@ namespace pan
       const_iterator begin(const Quark& q) const
                                         { return const_iterator(q,*this,0); }
       const_iterator end(const Quark& q) const
-                            { return const_iterator(q,*this,n_parts_found); }
+                            { return const_iterator(q, *this, parts.size()); }
 
     public:
       Parts ();
@@ -104,9 +104,9 @@ namespace pan
       Parts& operator= (const Parts&);
 
     public:
-      void set_part_count (number_t num) { n_parts_total = num; }
+      void set_part_count (number_t num) { n_parts_total = num; parts.reserve(num); }
       number_t get_total_part_count () const { return n_parts_total; }
-      number_t get_found_part_count () const { return n_parts_found; }
+      number_t get_found_part_count () const { return parts.size(); }
       void clear ();
       bool add_part (number_t num,
                      const StringView& mid,