Add begin and end to buffer types so Ranges can iterate their bytes.

Add warning about gather write use case.

Restore detail::append_path_info().

6 files changed, 93 insertions, 8 deletions

diff --git a/example/use_cases.cpp b/example/use_cases.cpp
index 1df10604..b8f93bee 100644
--- a/example/use_cases.cpp
+++ b/example/use_cases.cpp
@@ -153,6 +153,12 @@ void read_entire_file2()
 
 void scatter_write()
 {
+  /* WARNING: This example cannot possibly work because files opened with caching::only_metadata
+  are required by the operating system to be supplied with buffers aligned to, and be a multiple of,
+  the device's native block size (often 4Kb). So the gather buffers below would need to be each 4Kb
+  long, and aligned to 4Kb boundaries. If you would like this example to work as-is, change the
+  caching::only_metadata to caching::all.
+  */
   //! [scatter_write]
   namespace afio = AFIO_V2_NAMESPACE;
 
diff --git a/include/afio/revision.hpp b/include/afio/revision.hpp
index bac272df..010d0d38 100644
--- a/include/afio/revision.hpp
+++ b/include/afio/revision.hpp
@@ -1,4 +1,4 @@
 // Note the second line of this file must ALWAYS be the git SHA, third line ALWAYS the git SHA update time
-#define AFIO_PREVIOUS_COMMIT_REF    4547cc6a15ddb63e0dbe337d166ed9a817c65a92
-#define AFIO_PREVIOUS_COMMIT_DATE   "2018-06-24 16:29:15 +00:00"
-#define AFIO_PREVIOUS_COMMIT_UNIQUE 4547cc6a
+#define AFIO_PREVIOUS_COMMIT_REF    6321c6aa08472a02862f0aa1b66cdc4bbf0a891b
+#define AFIO_PREVIOUS_COMMIT_DATE   "2018-06-25 08:42:40 +00:00"
+#define AFIO_PREVIOUS_COMMIT_UNIQUE 6321c6aa
diff --git a/include/afio/v2.0/io_handle.hpp b/include/afio/v2.0/io_handle.hpp
index 8f46c622..2ada9efa 100644
--- a/include/afio/v2.0/io_handle.hpp
+++ b/include/afio/v2.0/io_handle.hpp
@@ -55,6 +55,10 @@ public:
   {
     //! Type of the pointer to memory.
     using pointer = byte *;
+    //! Type of the iterator to memory.
+    using iterator = byte *;
+    //! Type of the iterator to memory.
+    using const_iterator = const byte *;
     //! Type of the length of memory.
     using size_type = size_t;
 
@@ -62,12 +66,29 @@ public:
     pointer data;
     //! The number of bytes to fill into this address. Try to make this a 64 byte multiple, or ideally, a whole multiple of `page_size()`.
     size_type len;
+
+    //! Returns an iterator to the beginning of the buffer
+    constexpr iterator begin() { return data; }
+    //! Returns an iterator to the beginning of the buffer
+    constexpr const_iterator begin() const { return data; }
+    //! Returns an iterator to the beginning of the buffer
+    constexpr const_iterator cbegin() const { return data; }
+    //! Returns an iterator to after the end of the buffer
+    constexpr iterator end() { return data + len; }
+    //! Returns an iterator to after the end of the buffer
+    constexpr const_iterator end() const { return data + len; }
+    //! Returns an iterator to after the end of the buffer
+    constexpr const_iterator cend() const { return data + len; }
   };
   //! The gather buffer type used by this handle. Guaranteed to be `TrivialType` and `StandardLayoutType`.
   struct const_buffer_type
   {
     //! Type of the pointer to memory.
     using pointer = const byte *;
+    //! Type of the iterator to memory.
+    using iterator = const byte *;
+    //! Type of the iterator to memory.
+    using const_iterator = const byte *;
     //! Type of the length of memory.
     using size_type = size_t;
 
@@ -75,6 +96,19 @@ public:
     pointer data;
     //! The number of bytes to write from this address. Try to make this a 64 byte multiple, or ideally, a whole multiple of `page_size()`.
     size_type len;
+
+    //! Returns an iterator to the beginning of the buffer
+    constexpr iterator begin() { return data; }
+    //! Returns an iterator to the beginning of the buffer
+    constexpr const_iterator begin() const { return data; }
+    //! Returns an iterator to the beginning of the buffer
+    constexpr const_iterator cbegin() const { return data; }
+    //! Returns an iterator to after the end of the buffer
+    constexpr iterator end() { return data + len; }
+    //! Returns an iterator to after the end of the buffer
+    constexpr const_iterator end() const { return data + len; }
+    //! Returns an iterator to after the end of the buffer
+    constexpr const_iterator cend() const { return data + len; }
   };
 #ifndef NDEBUG
   static_assert(std::is_trivial<buffer_type>::value, "buffer_type is not a trivial type!");
diff --git a/include/afio/v2.0/logging.hpp b/include/afio/v2.0/logging.hpp
index cd638563..76030684 100644
--- a/include/afio/v2.0/logging.hpp
+++ b/include/afio/v2.0/logging.hpp
@@ -290,4 +290,47 @@ AFIO_V2_NAMESPACE_END
 #define AFIO_LOG_ALL(inst, message)
 #endif
 
+
+#if !AFIO_EXPERIMENTAL_STATUS_CODE
+#ifndef AFIO_DISABLE_PATHS_IN_FAILURE_INFO
+AFIO_V2_NAMESPACE_BEGIN
+
+namespace detail
+{
+  template <class Src> inline void append_path_info(Src &src, std::string &ret)
+  {
+    if(QUICKCPPLIB_NAMESPACE::utils::thread::this_thread_id() == src._thread_id)
+    {
+      auto &tls = detail::tls_errored_results();
+      const char *path1 = tls.get(src._tls_path_id1), *path2 = tls.get(src._tls_path_id2);
+      if(path1 != nullptr)
+      {
+        ret.append(" [path1 = ");
+        ret.append(path1);
+        if(path2 != nullptr)
+        {
+          ret.append(", path2 = ");
+          ret.append(path2);
+        }
+        ret.append("]");
+      }
+    }
+#if AFIO_LOGGING_LEVEL >= 2
+    if(src._log_id != static_cast<uint32_t>(-1))
+    {
+      if(log().valid(src._log_id))
+      {
+        ret.append(" [location = ");
+        ret.append(location(log()[src._log_id]));
+        ret.append("]");
+      }
+    }
+#endif
+  }
+}
+
+AFIO_V2_NAMESPACE_END
+#endif
+#endif
+
 #endif
diff --git a/include/afio/v2.0/status_code.hpp b/include/afio/v2.0/status_code.hpp
index 3b86db31..14b089f1 100644
--- a/include/afio/v2.0/status_code.hpp
+++ b/include/afio/v2.0/status_code.hpp
@@ -345,6 +345,7 @@ AFIO_V2_NAMESPACE_BEGIN
 namespace detail
 {
   template <class Dest, class Src> inline void fill_failure_info(Dest &dest, const Src &src);
+  template <class Src> inline void append_path_info(Src &src, std::string &ret);
 }
 
 struct error_info;
diff --git a/programs/benchmark-iostreams/main.cpp b/programs/benchmark-iostreams/main.cpp
index 58012955..8c680a14 100644
--- a/programs/benchmark-iostreams/main.cpp
+++ b/programs/benchmark-iostreams/main.cpp
@@ -22,7 +22,8 @@ Distributed under the Boost Software License, Version 1.0.
           http://www.boost.org/LICENSE_1_0.txt)
 */
 
-#define MAXBLOCKSIZE (256 * 1024)
+#define MINBLOCKSIZE (4096)
+#define MAXBLOCKSIZE (4096)
 #define REGIONSIZE (100 * 1024 * 1024)
 
 #include "../../include/afio/afio.hpp"
@@ -102,9 +103,9 @@ template <class F> inline void run_test(const char *csv, off_t max_extent, F &&f
   char buffer[MAXBLOCKSIZE];
   std::vector<std::pair<unsigned, unsigned>> offsets(512 * 1024);
   std::vector<std::vector<unsigned>> results;
-  for(size_t blocksize = 1; blocksize <= MAXBLOCKSIZE; blocksize <<= 1)
+  for(size_t blocksize = MINBLOCKSIZE; blocksize <= MAXBLOCKSIZE; blocksize <<= 1)
   {
-    size_t scale = blocksize / 16;
+    size_t scale = (512 * 1024) / (REGIONSIZE / blocksize) / 10;  // On average tap each block ten times
     if(scale < 1)
       scale = 1;
     small_prng rand;
@@ -127,7 +128,7 @@ template <class F> inline void run_test(const char *csv, off_t max_extent, F &&f
     }
   }
   std::ofstream out(csv);
-  for(size_t blocksize = 1; blocksize <= MAXBLOCKSIZE; blocksize <<= 1)
+  for(size_t blocksize = MINBLOCKSIZE; blocksize <= MAXBLOCKSIZE; blocksize <<= 1)
   {
     out << "," << blocksize;
   }
@@ -135,7 +136,7 @@ template <class F> inline void run_test(const char *csv, off_t max_extent, F &&f
   for(size_t n = 0; n < offsets.size(); n++)
   {
     auto it = results.cbegin();
-    for(size_t blocksize = 1; blocksize <= MAXBLOCKSIZE; blocksize <<= 1, ++it)
+    for(size_t blocksize = MINBLOCKSIZE; blocksize <= MAXBLOCKSIZE; blocksize <<= 1, ++it)
     {
       if(n < it->size())
         out << "," << it->at(n);