Removing lua_reader and lua_writer from StreamBuffer

luprex/cpp/core/luasnap.cpp

@@ -75,7 +75,8 @@ void LuaSnap::serialize(StreamBuffer *sb) {
     // Write dummy length, use eris to write data, then overwrite length.
     sb->write_int64(0);
     int64_t pos1 = sb->total_writes();
-    eris_dump(state_, sb->lua_writer, sb->lua_writer_ud());
+
+    eris_dump(state_, lua_writer_into_streambuffer, sb);
     int64_t pos2 = sb->total_writes();
     sb->overwrite_int64(pos1, pos2 - pos1);
     lua_settop(state_, 0);
@@ -85,14 +86,15 @@ void LuaSnap::deserialize(StreamBuffer *sb) {
     // Lua stack should be empty.
     assert(lua_gettop(state_) == 0);
 
-    // Get the length of the eris dump.
+    // Get the eris data and convert it to a LuaByteReader.
-    int64_t len = sb->read_int64();
+    int64_t eris_len = sb->read_int64();
-    void *ud = sb->lua_reader_ud(len);
+    const char *eris_bytes = sb->read_bytes(eris_len);
-
+    LuaByteReader bytereader(eris_bytes, eris_len);
+    
     // Call eris with the permanents table and passing the snapshot as a lua_Reader.
     lua_pushstring(state_, "unpersist");
     lua_rawget(state_, LUA_REGISTRYINDEX);
-    eris_undump(state_, sb->lua_reader, ud);
+    eris_undump(state_, bytereader.lua_reader, bytereader.lua_reader_userdata());
 
     // Set up a stack frame manually.  Eris deserialization
     // should have left permstable and regcopy on the stack.

luprex/cpp/core/luastack.cpp

@@ -559,3 +559,12 @@ void LuaKeywordParser::final_check_throw() {
         luaL_error(L_, "%s", err.c_str());
     }
 }
+
+const char *LuaByteReader::lua_reader(lua_State *L, void *ud, size_t *size) {
+    LuaByteReader *reader = (LuaByteReader*)ud;
+    *size = reader->size_;
+    const char *data = reader->data_;
+    reader->data_ = 0;
+    reader->size_ = 0;
+    return data;
+}

luprex/cpp/core/luastack.hpp

@@ -724,6 +724,24 @@ public:
     lua_State *state() const { return L_; }
 };
 
+////////////////////////////////////////////////////////////////////
+//
+// Lua Byte Reader
+//
+// Converts a block of bytes in RAM into a lua_reader.
+//
+////////////////////////////////////////////////////////////////////
+
+class LuaByteReader {
+private:
+    const char *data_;
+    int64_t size_;
+public:
+    LuaByteReader(const char *d, int64_t s) : data_(d), size_(s) {}
+    void *lua_reader_userdata() { return this; }
+    static const char *lua_reader(lua_State *L, void *ud, size_t *size);
+};
+
 ////////////////////////////////////////////////////////////////////
 //
 // The Lua Constant Registry

luprex/cpp/core/streambuffer.cpp

@@ -15,8 +15,6 @@ void StreamBuffer::init(bool fixed, bool owned, char *buf, int64_t size) {
     pre_read_count_ = 0;
     owned_ = owned;
     fixed_size_ = fixed;
-    lua_reader_data_ = 0;
-    lua_reader_size_ = 0;
 }
 
 StreamBuffer::StreamBuffer() {
@@ -80,8 +78,6 @@ void StreamBuffer::make_space_slow(int64_t bytes) {
 
     // Update some simple things.
     pre_read_count_ += (read_cursor_ - buf_lo_);
-    lua_reader_data_ = 0;
-    lua_reader_size_ = 0;
 
     // Move the data to the beginning of the buffer, or to
     // the beginning of a new buffer.
@@ -128,8 +124,6 @@ void StreamBuffer::clear() {
     read_cursor_ = buf_lo_;
     write_cursor_ = buf_lo_;
     pre_read_count_ = 0;
-    lua_reader_data_ = 0;
-    lua_reader_size_ = 0;
 }
 
 eng::string StreamBuffer::readline() {
@@ -341,34 +335,6 @@ util::HashValue StreamBuffer::hash() const {
     return std::make_pair(hash1, hash2);
 }
 
-int StreamBuffer::lua_writer(lua_State *L, const void* p, size_t sz, void* ud) {
-    StreamBuffer *sb = (StreamBuffer *)ud;
-    memcpy(sb->make_space(sz), p, sz);
-    sb->write_cursor_ += sz;
-    return 0;
-}
-
-void *StreamBuffer::lua_writer_ud() {
-    return this;
-}
-
-const char *StreamBuffer::lua_reader(lua_State *L, void *ud, size_t *size) {
-    StreamBuffer *sb = (StreamBuffer *)ud;
-    *size = sb->lua_reader_size_;
-    const char *data = sb->lua_reader_data_;
-    // Next time the reader gets called, there's no data left.
-    sb->lua_reader_data_ = 0;
-    sb->lua_reader_size_ = 0;
-    return data;
-}
-
-void *StreamBuffer::lua_reader_ud(int64_t size) {
-    const char *data = read_bytes(size);
-    lua_reader_data_ = data;
-    lua_reader_size_ = size;
-    return this;
-}
-
 class StreamBufferWriter : public std::streambuf, public eng::opnew {
 private:
     StreamBuffer *target_;
@@ -401,6 +367,13 @@ std::ostream &StreamBuffer::ostream() {
     return *ostream_;
 }
 
+int lua_writer_into_streambuffer(lua_State *L, const void* bytes, size_t sz, void* sbv) {
+    StreamBuffer *sb = (StreamBuffer *)sbv;
+    memcpy(sb->make_space(sz), bytes, sz);
+    sb->wrote_space(sz);
+    return 0;
+}
+
 static bool streq(const char *str, const char *data) {
     int len = strlen(str);
     return memcmp(str, data, len) == 0;

luprex/cpp/core/streambuffer.hpp

@@ -266,6 +266,17 @@ public:
     // Get the total number of bytes ever written to this buffer.
     int64_t total_writes() const;
 
+    // Make the specified amount of space in the buffer for writing.
+    // Return a pointer to the space.
+    char *make_space(int64_t bytes) {
+        int64_t available = buf_hi_ - write_cursor_;
+        if (available < bytes) make_space_slow(bytes);
+        return write_cursor_;
+    }
+
+    // Used after calling make_space then filling the space.
+    void wrote_space(int64_t bytes);
+
     // Amount of data inside the buffer.
     int64_t fill() const;
     
@@ -374,14 +385,6 @@ public:
     // Calculate a noncryptographic but good hash of what's in the buffer.
     util::HashValue hash() const;
 
-    // Use the stream buffer as a lua_Writer.
-    static int lua_writer(lua_State *L, const void* p, size_t sz, void* ud);
-    void *lua_writer_ud();
-    
-    // Use the stream buffer as a lua_Reader.
-    static const char *lua_reader(lua_State *L, void *data, size_t *size);
-    void *lua_reader_ud(int64_t bytes);
-
     // Get an ostream that writes into the StreamBuffer.
     std::ostream &ostream();
 
@@ -407,26 +410,13 @@ private:
     // True if we're not allowed to expand this buffer.
     bool fixed_size_;
 
-    // Lua reader return value.
-    const char *lua_reader_data_;
-    int64_t lua_reader_size_;
-
     // The ostream.  Only allocated on demand.
     std::unique_ptr<std::ostream> ostream_;
 
     // Initialize with a new buffer.
     void init(bool fixed, bool owned, char *buf, int64_t size);
 
-    // Make the specified amount of space in the buffer for writing.
-    // Return a pointer to the space.
-    char *make_space(int64_t bytes) {
-        int64_t available = buf_hi_ - write_cursor_;
-        if (available < bytes) make_space_slow(bytes);
-        return write_cursor_;
-    }
     void make_space_slow(int64_t bytes);
-
-    void wrote_space(int64_t bytes);
     
     // Implementation for the overwrite_int functions.
     char *get_overwrite(int64_t size, int64_t write_count_after);
@@ -437,4 +427,7 @@ private:
     friend int lfn_unittests_streambuffer(lua_State *L);
 };
 
+// Use a streambuffer as a lua_writer.
+int lua_writer_into_streambuffer(lua_State *L, const void* bytes, size_t sz, void* sb);
+
 #endif // STREAMBUFFER_HPP