factored buffer.h out of block.h

persistent-data/block.h

@@ -19,6 +19,7 @@
 #ifndef BLOCK_H
 #define BLOCK_H
 
+#include "persistent-data/buffer.h"
 #include "persistent-data/cache.h"
 #include "persistent-data/lock_tracker.h"
 
@@ -36,74 +37,8 @@
 //----------------------------------------------------------------
 
 namespace persistent_data {
-
-	uint32_t const MD_BLOCK_SIZE = 4096;
-
 	typedef uint64_t block_address;
 
-	// Heinz: could you move this to a separate file.  Add a big
-	// comment explaining that you should allocate it on the heap if
-	// you want the alignment guarantees.  Then write a test suite
-	// (buffer_t) that covers the following cases.
-	//
-	// - Allocate several on the heap, check they have the requested
-	//   alignment.  Try for various Alignments.  If memalign has
-	//   restrictions could you document (eg, power of 2).
-
-	// - you can use the [] to set a value in a non-const instance
-
-	// - you can't use the [] to set a value in a const instance - not
-	//   sure how to do this, since it'll be a compile time error.
-
-	// - you can use [] to read back a value that you've set.
-
-	// - [] to read works in a const instance.
-
-	// - you can use raw() to get and set values.
-
-	// - an exception is thrown if you put too large an index in []
-
-	// - check you can't copy a buffer via a copy constructor or ==
-	// - (again a compile time error, just experiment so you understand
-	// - boost::noncopyable).
-
-	template <uint32_t BlockSize = MD_BLOCK_SIZE, uint32_t Alignment = 512>
-	class buffer : private boost::noncopyable {
-	public:
-		unsigned char &operator[](unsigned index) {
-			if (index >= BlockSize)
-				throw std::runtime_error("buffer index out of bounds");
-
-			return data_[index];
-		}
-
-		unsigned char const &operator[](unsigned index) const {
-			if (index >= BlockSize)
-				throw std::runtime_error("buffer index out of bounds");
-
-			return data_[index];
-		}
-
-		unsigned char *raw() {
-			return data_;
-		}
-
-		unsigned char const *raw() const {
-			return data_;
-		}
-
-		static void *operator new(size_t s) {
-			return ::memalign(Alignment, s);
-		}
-
-		static void operator delete(void *p) {
-			free(p);
-		}
-
-	private:
-		unsigned char data_[BlockSize];
-	};
-
 	template <uint32_t BlockSize = MD_BLOCK_SIZE>
 	class block_io : private boost::noncopyable {
 	public: