From 69b77b6fde32cdf5dcaeeb92996bf6c4697e0b4f Mon Sep 17 00:00:00 2001 From: Roberto Ierusalimschy Date: Tue, 6 Sep 2022 10:58:55 -0300 Subject: Changed the growth rate of string buffers The growth rate of string buffers was reduced from 2 to 1.5 (3/2). As string buffers start larger (256~1024 bytes), they don't need to grow that fast. Moreover, a lower rate allows multiplicative growth up to larger sizes (3/2 of the maximum). (After that, the growth becomes linear, which is mostly useless.) --- lauxlib.c | 8 ++++---- luaconf.h | 5 +++-- 2 files changed, 7 insertions(+), 6 deletions(-) diff --git a/lauxlib.c b/lauxlib.c index cba5df9b..4ca6c654 100644 --- a/lauxlib.c +++ b/lauxlib.c @@ -526,14 +526,14 @@ static void newbox (lua_State *L) { /* ** Compute new size for buffer 'B', enough to accommodate extra 'sz' -** bytes. (The test for "double is not big enough" also gets the -** case when the multiplication by 2 overflows.) +** bytes. (The test for "not big enough" also gets the case when the +** computation of 'newsize' overflows.) */ static size_t newbuffsize (luaL_Buffer *B, size_t sz) { - size_t newsize = B->size * 2; /* double buffer size */ + size_t newsize = (B->size / 2) * 3; /* buffer size * 1.5 */ if (l_unlikely(MAX_SIZET - sz < B->n)) /* overflow in (B->n + sz)? */ return luaL_error(B->L, "buffer too large"); - if (newsize < B->n + sz) /* double is not big enough? */ + if (newsize < B->n + sz) /* not big enough? */ newsize = B->n + sz; return newsize; } diff --git a/luaconf.h b/luaconf.h index fcc0018b..e4650fbc 100644 --- a/luaconf.h +++ b/luaconf.h @@ -747,14 +747,15 @@ /* @@ LUA_IDSIZE gives the maximum size for the description of the source -@@ of a function in debug information. +** of a function in debug information. ** CHANGE it if you want a different size. */ #define LUA_IDSIZE 60 /* -@@ LUAL_BUFFERSIZE is the buffer size used by the lauxlib buffer system. +@@ LUAL_BUFFERSIZE is the initial buffer size used by the lauxlib +** buffer system. */ #define LUAL_BUFFERSIZE ((int)(16 * sizeof(void*) * sizeof(lua_Number))) -- cgit v1.2.1