# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1616110111 -3600
# Node ID 256810aa88c49a8d39ef0ccaecfcffee7f15ba44
# Parent  0073e2ca6c75cf24c2093d5624deb2da4f63c67b
Introduced common functionality for accessors, with methods for filling and
flushing populated regions of flexpages being invoked from the common fill and
flush methods.

diff -r 0073e2ca6c75 -r 256810aa88c4 accessor.cc
--- a/accessor.cc	Thu Mar 18 00:59:55 2021 +0100
+++ b/accessor.cc	Fri Mar 19 00:28:31 2021 +0100
@@ -1,5 +1,9 @@
 #include "accessor.h"
 
+#include <string.h>
+
+
+
 Accessor::Accessor(fileid_t fileid, offset_t size)
 : _size(size), fileid(fileid)
 {
@@ -31,4 +35,37 @@
 {
 }
 
+/* Data transfer methods. */
+
+void Accessor::fill(Flexpage *flexpage)
+{
+    /* Filling completely beyond the end of file should produce an empty
+       flexpage. This could potentially be a shared read-only flexpage that
+       would be replaced by an independent writable flexpage if ever written. */
+
+    if (flexpage->base_offset < _size)
+        fill_populated(flexpage);
+    else
+        memset((void *) flexpage->base_addr, 0, flexpage->size);
+}
+
+void Accessor::flush(Flexpage *flexpage)
+{
+    /* Flushing completely beyond the end of file should discard the
+       flexpage. */
+
+    if (flexpage->base_offset < _size)
+        flush_populated(flexpage);
+}
+
+/* Data transfer helper methods. */
+
+void Accessor::fill_populated(Flexpage *flexpage)
+{
+}
+
+void Accessor::flush_populated(Flexpage *flexpage)
+{
+}
+
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r 0073e2ca6c75 -r 256810aa88c4 accessor.h
--- a/accessor.h	Thu Mar 18 00:59:55 2021 +0100
+++ b/accessor.h	Fri Mar 19 00:28:31 2021 +0100
@@ -9,6 +9,12 @@
 protected:
     offset_t _size;
 
+    /* Data transfer helper methods. */
+
+    virtual void fill_populated(Flexpage *flexpage);
+
+    virtual void flush_populated(Flexpage *flexpage);
+
 public:
     fileid_t fileid;
 
@@ -24,9 +30,9 @@
 
     /* Data transfer methods. */
 
-    virtual void fill(Flexpage *flexpage) = 0;
+    virtual void fill(Flexpage *flexpage);
 
-    virtual void flush(Flexpage *flexpage) = 0;
+    virtual void flush(Flexpage *flexpage);
 };
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r 0073e2ca6c75 -r 256810aa88c4 files/block_file_accessor.cc
--- a/files/block_file_accessor.cc	Thu Mar 18 00:59:55 2021 +0100
+++ b/files/block_file_accessor.cc	Fri Mar 19 00:28:31 2021 +0100
@@ -62,27 +62,15 @@
     }
 }
 
-/* Data transfer methods. */
+/* Data transfer helper methods. */
 
-void BlockFileAccessor::fill(Flexpage *flexpage)
+/* Fill the populated portion of a flexpage. */
+
+void BlockFileAccessor::fill_populated(Flexpage *flexpage)
 {
     offset_t filepos = flexpage->base_offset;
     offset_t addr = flexpage->base_addr;
-    offset_t populated_size;
-
-    /* Filling completely beyond the end of file should produce an empty
-       flexpage. This could potentially be a shared read-only flexpage that
-       would be replaced by an independent writable flexpage if ever written. */
-
-    if (filepos > _size)
-    {
-        memset((void *) addr, 0, flexpage->size);
-        return;
-    }
-
-    /* Otherwise, fill the populated portion of a flexpage. */
-
-    populated_size = std::min(flexpage->size, _size - filepos);
+    offset_t populated_size = std::min(flexpage->size, _size - filepos);
 
     /* Tag the region with file state. */
 
@@ -98,21 +86,13 @@
         memset((void *) (addr + populated_size), 0, flexpage->size - populated_size);
 }
 
-void BlockFileAccessor::flush(Flexpage *flexpage)
-{
-    offset_t addr = flexpage->base_addr;
-    offset_t filepos = flexpage->base_offset;
-    offset_t populated_size;
+/* Flush the populated portion of a flexpage. */
 
-    /* Flushing completely beyond the end of file should discard the
-       flexpage. */
-
-    if (filepos > _size)
-        return;
-
-    /* Otherwise, only the populated portion of a flexpage should be flushed. */
-
-    populated_size = std::min(flexpage->size, _size - filepos);
+void BlockFileAccessor::flush_populated(Flexpage *flexpage)
+{
+    offset_t filepos = flexpage->base_offset;
+    offset_t addr = flexpage->base_addr;
+    offset_t populated_size = std::min(flexpage->size, _size - filepos);
 
     /* Remove the file state tag from the region. */
 
diff -r 0073e2ca6c75 -r 256810aa88c4 files/block_file_accessor.h
--- a/files/block_file_accessor.h	Thu Mar 18 00:59:55 2021 +0100
+++ b/files/block_file_accessor.h	Fri Mar 19 00:28:31 2021 +0100
@@ -10,16 +10,16 @@
 protected:
     char *_data;
 
+    /* Data transfer helper methods. */
+
+    virtual void fill_populated(Flexpage *flexpage);
+
+    virtual void flush_populated(Flexpage *flexpage);
+
 public:
     explicit BlockFileAccessor(const char *path, fileid_t fileid);
 
     virtual void set_size(offset_t size);
-
-    /* Data transfer methods. */
-
-    virtual void fill(Flexpage *flexpage);
-
-    virtual void flush(Flexpage *flexpage);
 };
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r 0073e2ca6c75 -r 256810aa88c4 files/host_file_accessor.cc
--- a/files/host_file_accessor.cc	Thu Mar 18 00:59:55 2021 +0100
+++ b/files/host_file_accessor.cc	Fri Mar 19 00:28:31 2021 +0100
@@ -32,13 +32,14 @@
     _fp = fopen(_path, "r");
 }
 
-/* Data transfer methods. */
+/* Data transfer helper methods. */
 
-void HostFileAccessor::fill(Flexpage *flexpage)
+void HostFileAccessor::fill_populated(Flexpage *flexpage)
 {
-    /* Obtain the offset and seek in the file. */
+    offset_t filepos = flexpage->base_offset;
+    offset_t addr = flexpage->base_addr;
 
-    offset_t filepos = flexpage->base_offset;
+    /* Seek to the offset in the file. */
 
     fseek(_fp, filepos, SEEK_SET);
 
@@ -48,8 +49,6 @@
 
     /* Fill the region with file content. */
 
-    offset_t addr = flexpage->base_addr;
-
     size_t nread = fread((void *) addr, sizeof(char), flexpage->size, _fp);
 
     /* Pad the flexpage with zero. */
@@ -57,11 +56,8 @@
     memset((void *) (addr + nread), 0, flexpage->size - nread);
 }
 
-void HostFileAccessor::flush(Flexpage *flexpage)
+void HostFileAccessor::flush_populated(Flexpage *flexpage)
 {
-    /* NOTE: A real flush operation would store the memory content and update
-             the file size, if appropriate. */
-
     flexpage->region->flush();
 }
 
diff -r 0073e2ca6c75 -r 256810aa88c4 files/host_file_accessor.h
--- a/files/host_file_accessor.h	Thu Mar 18 00:59:55 2021 +0100
+++ b/files/host_file_accessor.h	Fri Mar 19 00:28:31 2021 +0100
@@ -13,18 +13,18 @@
     const char *_path;
     FILE *_fp;
 
+    /* Data transfer helper methods. */
+
+    virtual void fill_populated(Flexpage *flexpage);
+
+    virtual void flush_populated(Flexpage *flexpage);
+
 public:
     explicit HostFileAccessor(const char *path, fileid_t fileid);
 
     virtual void close();
 
     virtual void open();
-
-    /* Data transfer methods. */
-
-    virtual void fill(Flexpage *flexpage);
-
-    virtual void flush(Flexpage *flexpage);
 };
 
 // vim: tabstop=4 expandtab shiftwidth=4
diff -r 0073e2ca6c75 -r 256810aa88c4 files/test_file_accessor.cc
--- a/files/test_file_accessor.cc	Thu Mar 18 00:59:55 2021 +0100
+++ b/files/test_file_accessor.cc	Fri Mar 19 00:28:31 2021 +0100
@@ -8,9 +8,9 @@
 {
 }
 
-/* Data transfer methods. */
+/* Data transfer helper methods. */
 
-void TestFileAccessor::fill(Flexpage *flexpage)
+void TestFileAccessor::fill_populated(Flexpage *flexpage)
 {
     Region *region = flexpage->region;
     offset_t filepos = flexpage->base_offset;
@@ -43,11 +43,8 @@
     }
 }
 
-void TestFileAccessor::flush(Flexpage *flexpage)
+void TestFileAccessor::flush_populated(Flexpage *flexpage)
 {
-    /* NOTE: Flushing would not necessarily blank the region as this does.
-             Also, a real flush operation would store the memory content. */
-
     flexpage->region->flush();
 }
 
diff -r 0073e2ca6c75 -r 256810aa88c4 files/test_file_accessor.h
--- a/files/test_file_accessor.h	Thu Mar 18 00:59:55 2021 +0100
+++ b/files/test_file_accessor.h	Fri Mar 19 00:28:31 2021 +0100
@@ -6,14 +6,16 @@
 
 class TestFileAccessor : public Accessor
 {
+protected:
+
+    /* Data transfer helper methods. */
+
+    virtual void fill_populated(Flexpage *flexpage);
+
+    virtual void flush_populated(Flexpage *flexpage);
+
 public:
     explicit TestFileAccessor(fileid_t fileid, offset_t size=0);
-
-    /* Data transfer methods. */
-
-    virtual void fill(Flexpage *flexpage);
-
-    virtual void flush(Flexpage *flexpage);
 };
 
 // vim: tabstop=4 expandtab shiftwidth=4