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prosody
File
util-src/ringbuffer.c @ 13174:8ec7b7d6556f
util.cache: Keep eviction candidate if callback resized to make room
Previously either the old or the new values would be rejected, even if
the cache was resized to allow more items.
author | Kim Alvefur <zash@zash.se> |
---|---|
date | Fri, 30 Jun 2023 22:01:49 +0200 |
parent | 12976:a187600ec7d6 |
line wrap: on
line source
#include <stdlib.h> #include <unistd.h> #include <string.h> #include <lua.h> #include <lauxlib.h> #if (LUA_VERSION_NUM < 504) #define luaL_pushfail lua_pushnil #endif typedef struct { size_t rpos; /* read position */ size_t wpos; /* write position */ size_t alen; /* allocated size */ size_t blen; /* current content size */ char buffer[]; } ringbuffer; /* Translate absolute idx to a wrapped index within the buffer, based on current read position */ static int wrap_pos(const ringbuffer *b, const long idx, long *pos) { if(idx > (long)b->blen) { return 0; } if(idx + (long)b->rpos > (long)b->alen) { *pos = idx - (b->alen - b->rpos); } else { *pos = b->rpos + idx; } return 1; } static int calc_splice_positions(const ringbuffer *b, long start, long end, long *out_start, long *out_end) { if(start < 0) { start = 1 + start + b->blen; } if(start <= 0) { start = 1; } if(end < 0) { end = 1 + end + b->blen; } if(end > (long)b->blen) { end = b->blen; } if(start < 1) { start = 1; } if(start > end) { return 0; } start = start - 1; if(!wrap_pos(b, start, out_start)) { return 0; } if(!wrap_pos(b, end, out_end)) { return 0; } return 1; } static void writechar(ringbuffer *b, char c) { b->blen++; b->buffer[(b->wpos++) % b->alen] = c; } /* make sure position counters stay within the allocation */ static void modpos(ringbuffer *b) { b->rpos = b->rpos % b->alen; b->wpos = b->wpos % b->alen; } static int find(ringbuffer *b, const char *s, size_t l) { size_t i, j; int m; if(b->rpos == b->wpos) { /* empty */ return 0; } /* look for a matching first byte */ for(i = 0; i <= b->blen - l; i++) { if(b->buffer[(b->rpos + i) % b->alen] == *s) { m = 1; /* check if the following byte also match */ for(j = 1; j < l; j++) if(b->buffer[(b->rpos + i + j) % b->alen] != s[j]) { m = 0; break; } if(m) { return i + l; } } } return 0; } /* * Find first position of a substring in buffer * (buffer, string) -> number */ static int rb_find(lua_State *L) { size_t l, m; ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt"); const char *s = luaL_checklstring(L, 2, &l); m = find(b, s, l); if(m > 0) { lua_pushinteger(L, m); return 1; } return 0; } /* * Move read position forward without returning the data * (buffer, number) -> boolean */ static int rb_discard(lua_State *L) { ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt"); size_t r = luaL_checkinteger(L, 2); if(r > b->blen) { lua_pushboolean(L, 0); return 1; } b->blen -= r; b->rpos += r; modpos(b); lua_pushboolean(L, 1); return 1; } /* * Read bytes from buffer * (buffer, number, boolean?) -> string */ static int rb_read(lua_State *L) { ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt"); size_t r = luaL_checkinteger(L, 2); int peek = lua_toboolean(L, 3); if(r > b->blen) { luaL_pushfail(L); return 1; } if((b->rpos + r) > b->alen) { /* Substring wraps around to the beginning of the buffer */ lua_pushlstring(L, &b->buffer[b->rpos], b->alen - b->rpos); lua_pushlstring(L, b->buffer, r - (b->alen - b->rpos)); lua_concat(L, 2); } else { lua_pushlstring(L, &b->buffer[b->rpos], r); } if(!peek) { b->blen -= r; b->rpos += r; modpos(b); } return 1; } /* * Read buffer until first occurrence of a substring * (buffer, string) -> string */ static int rb_readuntil(lua_State *L) { size_t l, m; ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt"); const char *s = luaL_checklstring(L, 2, &l); m = find(b, s, l); if(m > 0) { lua_settop(L, 1); lua_pushinteger(L, m); return rb_read(L); } return 0; } /* * Write bytes into the buffer * (buffer, string) -> integer */ static int rb_write(lua_State *L) { size_t l, w = 0; ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt"); const char *s = luaL_checklstring(L, 2, &l); /* Does `l` bytes fit? */ if((l + b->blen) > b->alen) { luaL_pushfail(L); return 1; } while(l-- > 0) { writechar(b, *s++); w++; } modpos(b); lua_pushinteger(L, w); return 1; } static int rb_tostring(lua_State *L) { ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt"); lua_pushfstring(L, "ringbuffer: %p %d/%d", b, b->blen, b->alen); return 1; } static int rb_sub(lua_State *L) { ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt"); long start = luaL_checkinteger(L, 2); long end = luaL_optinteger(L, 3, -1); long wrapped_start, wrapped_end; if(!calc_splice_positions(b, start, end, &wrapped_start, &wrapped_end)) { lua_pushstring(L, ""); } else if(wrapped_end <= wrapped_start) { lua_pushlstring(L, &b->buffer[wrapped_start], b->alen - wrapped_start); lua_pushlstring(L, b->buffer, wrapped_end); lua_concat(L, 2); } else { lua_pushlstring(L, &b->buffer[wrapped_start], (wrapped_end - wrapped_start)); } return 1; } static int rb_byte(lua_State *L) { ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt"); long start = luaL_optinteger(L, 2, 1); long end = luaL_optinteger(L, 3, start); long i; long wrapped_start, wrapped_end; if(calc_splice_positions(b, start, end, &wrapped_start, &wrapped_end)) { if(wrapped_end <= wrapped_start) { for(i = wrapped_start; i < (long)b->alen; i++) { lua_pushinteger(L, (unsigned char)b->buffer[i]); } for(i = 0; i < wrapped_end; i++) { lua_pushinteger(L, (unsigned char)b->buffer[i]); } return wrapped_end + (b->alen - wrapped_start); } else { for(i = wrapped_start; i < wrapped_end; i++) { lua_pushinteger(L, (unsigned char)b->buffer[i]); } return wrapped_end - wrapped_start; } } return 0; } static int rb_length(lua_State *L) { ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt"); lua_pushinteger(L, b->blen); return 1; } static int rb_size(lua_State *L) { ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt"); lua_pushinteger(L, b->alen); return 1; } static int rb_free(lua_State *L) { ringbuffer *b = luaL_checkudata(L, 1, "ringbuffer_mt"); lua_pushinteger(L, b->alen - b->blen); return 1; } static int rb_new(lua_State *L) { lua_Integer size = luaL_optinteger(L, 1, sysconf(_SC_PAGESIZE)); luaL_argcheck(L, size > 0, 1, "positive integer expected"); ringbuffer *b = lua_newuserdata(L, sizeof(ringbuffer) + size); b->rpos = 0; b->wpos = 0; b->alen = size; b->blen = 0; luaL_getmetatable(L, "ringbuffer_mt"); lua_setmetatable(L, -2); return 1; } int luaopen_prosody_util_ringbuffer(lua_State *L) { luaL_checkversion(L); if(luaL_newmetatable(L, "ringbuffer_mt")) { lua_pushcfunction(L, rb_tostring); lua_setfield(L, -2, "__tostring"); lua_pushcfunction(L, rb_length); lua_setfield(L, -2, "__len"); lua_createtable(L, 0, 7); /* __index */ { lua_pushcfunction(L, rb_find); lua_setfield(L, -2, "find"); lua_pushcfunction(L, rb_discard); lua_setfield(L, -2, "discard"); lua_pushcfunction(L, rb_read); lua_setfield(L, -2, "read"); lua_pushcfunction(L, rb_readuntil); lua_setfield(L, -2, "readuntil"); lua_pushcfunction(L, rb_write); lua_setfield(L, -2, "write"); lua_pushcfunction(L, rb_size); lua_setfield(L, -2, "size"); lua_pushcfunction(L, rb_length); lua_setfield(L, -2, "length"); lua_pushcfunction(L, rb_sub); lua_setfield(L, -2, "sub"); lua_pushcfunction(L, rb_byte); lua_setfield(L, -2, "byte"); lua_pushcfunction(L, rb_free); lua_setfield(L, -2, "free"); } lua_setfield(L, -2, "__index"); } lua_createtable(L, 0, 1); lua_pushcfunction(L, rb_new); lua_setfield(L, -2, "new"); return 1; } int luaopen_util_ringbuffer(lua_State *L) { return luaopen_prosody_util_ringbuffer(L); }