/*
userdata send_buffer
table pool
lightuserdata msg
int size
return size
Comment: The table pool record all the buffers chunk,
and the first index [1] is a lightuserdata : free_node. We can always use this pointer for struct buffer_node .
The following ([2] ...) userdatas in table pool is the buffer chunk (for struct buffer_node),
we never free them until the VM closed. The size of first chunk ([2]) is 8 struct buffer_node,
and the second size is 16 ... The largest size of chunk is LARGE_PAGE_NODE (4096)
lpushbbuffer will get a free struct buffer_node from table pool, and then put the msg/size in it.
lpopbuffer return the struct buffer_node back to table pool (By calling return_free_node).
*/
static int
lpushbuffer(lua_State *L) {
struct socket_buffer *sb = lua_touserdata(L,1);
if (sb == NULL) {
return luaL_error(L, "need buffer object at param 1");
}
char * msg = lua_touserdata(L,3);
if (msg == NULL) {
return luaL_error(L, "need message block at param 3");
}
int pool_index = 2;
luaL_checktype(L,pool_index,LUA_TTABLE);
int sz = luaL_checkinteger(L,4);
lua_rawgeti(L,pool_index,1);
struct buffer_node * free_node = lua_touserdata(L,-1); // sb poolt msg size free_node
lua_pop(L,1);
if (free_node == NULL) {
int tsz = lua_rawlen(L,pool_index);
if (tsz == 0)
tsz++;
int size = 8;
if (tsz <= LARGE_PAGE_NODE-3) {
size <<= tsz;
} else {
size <<= LARGE_PAGE_NODE-3;
}
lnewpool(L, size);
free_node = lua_touserdata(L,-1);
lua_rawseti(L, pool_index, tsz+1);
}
lua_pushlightuserdata(L, free_node->next);
lua_rawseti(L, pool_index, 1); // sb poolt msg size
free_node->msg = msg;
free_node->sz = sz;
free_node->next = NULL;
if (sb->head == NULL) {
assert(sb->tail == NULL);
sb->head = sb->tail = free_node;
} else {
sb->tail->next = free_node;
sb->tail = free_node;
}
sb->size += sz;
lua_pushinteger(L, sb->size);
return 1;
}
// local sz = driver.push(s.buffer, buffer_pool, data, size)
static int
lpushbuffer(lua_State *L) {
// 获取第一个参数值，缓冲区链表
struct socket_buffer *sb = lua_touserdata(L,1);
if (sb == NULL) {
return luaL_error(L, "need buffer object at param 1");
}
// 获取第三个参数值，消息数据
char * msg = lua_touserdata(L,3);
if (msg == NULL) {
return luaL_error(L, "need message block at param 3");
}
int pool_index = 2;
// 检查第二个参数是否为table类型
/*
local buffer_pool = {}
buffer_pool是在lua层(socket.lua)中创建并初始化空表
lua方法pop,push,readall,readline,clear中作为第二个参数传入
在lua绑定的c方法中，从栈中取出第二个元素，即可得到buffer_pool
buffer_pool[1]，存放的是一个lightuserdata，即缓冲区池第一个节点的地址，见lua_pushlightuserdata(L, free_node->next);
buffer_pool[2] ...，存放的是userdata，即固定大小的链表数组内存地址，见lua_rawseti(L, pool_index, tsz+1);
*/
luaL_checktype(L,pool_index,LUA_TTABLE);
// 获取第四个参数值，消息长度
int sz = luaL_checkinteger(L,4);
// 把缓冲池lua表的第一个元素压栈
lua_rawgeti(L,pool_index,1);
// 获取缓冲池lua表的第一个元素
// 准确地说是 获取第一个元素存放的指针 所指向的一段完全用户数据 其实就是一个缓冲区节点
struct buffer_node * free_node = lua_touserdata(L,-1); // sb poolt msg size free_node
// 把缓冲池lua表的第一个元素弹出栈
lua_pop(L,1);
if (free_node == NULL) {
// 如果获取到的缓冲区节点为空，说明buffer_pool[n]里的buffer_node已经用光
// 获取buffer_pool表的长度
// 初始为0，一直递增，直到vm重启
/*
tsz buffer_pool表的长度
index buffer_pool表的索引
size buffer_pool[index]存放buffer_node的数量
tsz size index
0 8 << 1 = 16 2
2 8 << 2 = 32 3
.
.
.
9 8 << 9 = 4096 10
10 8 << 9 = 4096 11
*/
int tsz = lua_rawlen(L,pool_index);
if (tsz == 0)
// 初始为0，预留buffer_pool[1]存放lightuserdata
tsz++;
int size = 8;
if (tsz <= LARGE_PAGE_NODE-3) {
size <<= tsz;
} else {
// 不超过4096，即2的12次方
size <<= LARGE_PAGE_NODE-3;
}
// 新建缓冲区池
// struct buffer_node * pool = lua_newuserdata(L, sizeof(struct buffer_node) * sz);
lnewpool(L, size);
// 获取新建缓冲区池第一个缓冲区节点
free_node = lua_touserdata(L,-1);
// 把新建的缓冲区池放到缓冲区池lua表的特定索引中
lua_rawseti(L, pool_index, tsz+1);
}
// 把缓冲池lua表的第一个元素的下一个元素压栈
lua_pushlightuserdata(L, free_node->next);
// 把缓冲池lua表的第一个元素的下一个元素设置为lua表的第一个元素，并弹出栈
lua_rawseti(L, pool_index, 1); // sb poolt msg size
// 以上操作从缓冲池中取出了一个缓冲区节点
// 缓冲区节点装入数据
free_node->msg = msg;
free_node->sz = sz;
free_node->next = NULL;
// 缓冲区节点加入链表
if (sb->head == NULL) {
assert(sb->tail == NULL);
sb->head = sb->tail = free_node;
} else {
sb->tail->next = free_node;
sb->tail = free_node;
}
sb->size += sz;
// 缓冲区链表数据总长度压栈并作为lua返回值
lua_pushinteger(L, sb->size);
return 1;
}
