From 14683979c43e17393dc4f902fe65ed22898b2bce Mon Sep 17 00:00:00 2001
From: Mike Buland <eichlan@xagasoft.com>
Date: Tue, 25 Jun 2019 20:00:47 -0700
Subject: BlobBuilder implemented, tests in progress.

---
 src/unstable/blobbuilder.cpp |  8 +++++---
 src/unstable/blobbuilder.h   | 20 ++++++++++++++++++++
 2 files changed, 25 insertions(+), 3 deletions(-)

(limited to 'src/unstable')

diff --git a/src/unstable/blobbuilder.cpp b/src/unstable/blobbuilder.cpp
index d4b458b..497a1a1 100644
--- a/src/unstable/blobbuilder.cpp
+++ b/src/unstable/blobbuilder.cpp
@@ -8,7 +8,7 @@
 #include "bu/blobbuilder.h"
 #include "bu/blob.h"
 
-#define PAGE_SIZE 1024
+#define PAGE_SIZE 8
 
 /////
 // BlobBuilderCore::Chunk
@@ -109,20 +109,20 @@ void Bu::BlobBuilderCore::clear()
         delete pCur;
         pCur = pNext;
     }
-    delete pFirst;
     pFirst = pLast = 0;
     iLength = 0;
 }
 
 void Bu::BlobBuilderCore::append( const char *pSrc, int32_t iLength )
 {
+    this->iLength += iLength;
     if( pFirst == 0 )
     {
         // Nothing in the list, just add a chunk.
         pFirst = pLast = new Chunk( pSrc, iLength );
         return;
     }
-    else if( pLast->iLength < 1024 )
+    else if( pLast->iLength < PAGE_SIZE )
     {
         // Append to the last chunk first, this will modify pSrc & iLength.
         pLast->append( pSrc, iLength );
@@ -147,6 +147,7 @@ void Bu::BlobBuilderCore::prepend( const char *pSrc, int32_t iLength )
         pNew->pNext = pFirst;
         pFirst = pNew;
     }
+    this->iLength += iLength;
 }
 
 void Bu::BlobBuilderCore::insert( int32_t iBefore, const char *pSrc,
@@ -185,6 +186,7 @@ void Bu::BlobBuilderCore::insert( int32_t iBefore, const char *pSrc,
         }
         pCur = pCur->pNext;
     }
+    this->iLength += iLength;
 }
 
 void Bu::BlobBuilderCore::set( const char *pSrc, int32_t iLength )
diff --git a/src/unstable/blobbuilder.h b/src/unstable/blobbuilder.h
index 483de43..744212a 100644
--- a/src/unstable/blobbuilder.h
+++ b/src/unstable/blobbuilder.h
@@ -61,6 +61,26 @@ namespace Bu
     };
     /** @endcond */
 
+    /**
+     * This makes creating a Blob piece at a time easy and fast.  You can
+     * append, prepend, or insert with reasonable efficiency. The underlying
+     * data structure is currently a linked list, and the individual links are
+     * actually block allocated memory. If an amount of data is appended that
+     * is less than the minimum page size then the minimum page size is
+     * allocated. Subsequent appends will share that allocated buffer until it
+     * is full, at which point a new buffer will be created.  If an amount
+     * greater than the minimum page size is appended then any extra space in
+     * the last buffer is used, and then the rest is placed in a single buffer.
+     * At most one buffer will be allocated for any given append or prepend
+     * operation.  Due to the nature of insert, up to two buffers could be
+     * allocated.
+     *
+     * Insert operations will take O(N) time to find the location to insert to
+     * in the linked list, at that point the foud chunk will be split into two
+     * and the new data will be added at the new location. This will also
+     * attempt to share the existing buffers, but if there's extra it will
+     * allocate a new buffer for the remaining data.
+     */
     class BlobBuilder : public Bu::SharedCore<BlobBuilder, BlobBuilderCore>
     {
     protected:
-- 
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