Prepare for more smart pointers: Move pointer arithmetic to a separate function.

native/src/impl/file.cpp

@@ -135,6 +135,47 @@ FileADT::_validate_readv(const ReadList& requests, std::int64_t eof, OpenMode mo
   }
 }
 
+/**
+ * Convenience function to invoke a delivery functor with optional
+ * pointer arithmetic, delivering just a part of the buffer.
+ *
+ * If and when the delivery function is changed to use a smart pointer:
+ *
+ * Optionally check that the called function did not retain a pointer
+ * to the data if it promised not to do that.
+ *
+ * If the contract about not retaining references is broken then raise
+ * an exception. Even if the code happens to have allocate a unique
+ * buffer so it doesn't really care. Note: In some cases, e.g. if a
+ * proper cache is involved, the functor might end up retaining a
+ * pointer aliased to the entire cache. Which would be fatal and would
+ * warrant an abort(). The code here will still just throw an
+ * exception, though.
+ *
+ * If the functor states that it needs to retain a pointer then make
+ * sure it gets a smart pointer that is aliased to the entire buffer.
+ */
+void
+FileADT::_deliver(
+     const ReadRequest::delivery_t& fn,
+     const void *data,
+     std::int64_t offset,
+     std::int64_t size,
+     bool transient)
+{
+  if (!data)
+    throw OpenZGY::Errors::ZgyInternalError("Attempt to deliver null data");
+  if (!fn)
+    return; // Caller doesn't need the data. This is ok.
+  if (offset == 0) {
+    fn(data, size);
+  }
+  else {
+    auto dumb_ptr  = static_cast<const char*>(data) + offset;
+    fn(dumb_ptr, size);
+  }
+}
+
 std::shared_ptr<FileADT>
 FileADT::factory(const std::string& filename, OpenMode mode, const IOContext *iocontext)
 {

native/src/impl/file.h

@@ -232,6 +232,8 @@ protected:
   static void _validate_read(void *data, std::int64_t offset, std::int64_t size, std::int64_t eof, OpenMode mode);
   static void _validate_write(const void *data, std::int64_t offset, std::int64_t size, OpenMode mode);
   static void _validate_readv(const ReadList& requests, std::int64_t eof, OpenMode mode);
+public: // Actually internal. Used by ConsolidateRequests.
+  static void _deliver(const ReadRequest::delivery_t& fn, const void *data, std::int64_t offset, std::int64_t size, bool transient);
 
 public:
   static std::shared_ptr<FileADT> factory(const std::string& filename, OpenMode mode, const OpenZGY::IOContext *iocontext);

native/src/impl/file_consolidate.cpp

@@ -362,7 +362,8 @@ ConsolidateRequests::_consolidated_delivery(
              if (rr.delivery) {
                std::int64_t end = std::min(rr.offset + rr.size - begin, size);
                std::int64_t beg = std::min(rr.offset - begin, end);
-               rr.delivery(static_cast<const char*>(data) + beg, end - beg);
+               // Caller will check the transient_ok flag. we won't.
+               FileADT::_deliver(rr.delivery, data, beg, end - beg, false);
              }
            }
          };

native/src/impl/file_local.cpp

@@ -258,7 +258,7 @@ LocalFileLinux::xx_readv(const ReadList& requests, bool parallel_ok, bool immuta
     for (const ReadRequest& r : requests) {
       std::shared_ptr<char> data(new char[r.size]);
       this->LocalFileLinux::xx_read(data.get(), r.offset, r.size, usagehint);
-      r.delivery(data.get(), r.size);
+      _deliver(r.delivery, data.get(), 0, r.size, transient_ok);
     }
   }
   else {
@@ -298,7 +298,7 @@ LocalFileLinux::xx_readv(const ReadList& requests, bool parallel_ok, bool immuta
         const ReadRequest& r = requests[ii];
         guard.run([&](){
           this->LocalFileLinux::xx_read(data.get(), r.offset, r.size, usagehint);
-          r.delivery(data.get(), r.size);
+          _deliver(r.delivery, data.get(), 0, r.size, transient_ok);
         });
       }
     }

native/src/impl/file_parallelizer.cpp

@@ -136,7 +136,7 @@ FileParallelizer::xx_readv(
   for (std::int64_t ii = 0; ii < requestcount; ++ii) {
     guard.run([&](){
       std::cerr << "0123456789"[omp_get_thread_num() % 10];
-      requests[ii].delivery(buffers[ii].get(), requests[ii].size);
+      _deliver(requests[ii].delivery, buffers[ii].get(), 0, requests[ii].size, transient_ok);
     });
   }
   guard.finished();

native/src/impl/file_sd.cpp

@@ -1155,7 +1155,7 @@ SeismicStoreFile::xx_readv(const ReadList& requests, bool parallel_ok, bool immu
   for (const ReadRequest& r : requests) {
     std::shared_ptr<char> data(new char[r.size]);
     this->SeismicStoreFile::xx_read(data.get(), r.offset, r.size, usagehint);
-    r.delivery(data.get(), r.size);
+    _deliver(r.delivery, data.get(), 0, r.size, transient_ok);
   }
   return;
 #endif
@@ -1296,8 +1296,7 @@ SeismicStoreFile::xx_readv(const ReadList& requests, bool parallel_ok, bool immu
     // TODO-Worry: If this_size != rr.size, can this ever happen?
     // If yes then we might have lost track of where in the buffer
     // we should copy out from. This wory also applies to the Python code.
-    if (rr.delivery)
-      rr.delivery(data.get() + pos, this_size);
+    _deliver(rr.delivery, data.get(), pos, this_size, transient_ok);
     pos += this_size;
   }
 }
@@ -1810,7 +1809,7 @@ SeismicStoreFileDelayedWrite::xx_readv(const ReadList& requests, bool parallel_o
     for (const ReadRequest& r : requests) {
       std::shared_ptr<char> data(new char[r.size]);
       this->SeismicStoreFileDelayedWrite::xx_read(data.get(), r.offset, r.size, usagehint);
-      r.delivery(data.get(), r.size);
+      _deliver(r.delivery, data.get(), 0, r.size, transient_ok);
     }
   }
 }

native/src/impl/file_windows.cpp

@@ -237,7 +237,7 @@ LocalFileWindows::xx_readv(const ReadList& requests, bool parallel_ok, bool immu
   for (const ReadRequest& r : requests) {
     std::unique_ptr<char> data(new char[r.size]);
     this->LocalFileWindows::xx_read(data.get(), r.offset, r.size, usagehint);
-    r.delivery(data.get(), r.size);
+    _deliver(r.delivery, data.get(), 0, r.size, transient_ok);
   }
 }
 

native/src/test/test_consolidate.cpp

@@ -175,7 +175,7 @@ run_test(const ReadList& list_in,
 
   // Deliver my data according to the consolidated list.
   for (const ReadRequest& rr : result)
-    rr.delivery(reinterpret_cast<char*>(data.data()) + rr.offset, rr.size);
+    FileADT::_deliver(rr.delivery, data.data(), rr.offset, rr.size, false);
 
   // Check that all the data that was originally requested
   // was delivered to the correct place in a timely manner.