From 9505cd15a64933bf58ec50548339cf98b1854646 Mon Sep 17 00:00:00 2001 From: Russ Cox Date: Tue, 14 Jan 2020 18:03:05 -0500 Subject: lib9: make formatting lock-free again First use of . We will see if any supported systems don't have it yet. (C11 was so last decade.) Fixes #338. --- src/lib9/fmt/fmt.c | 165 ++++++++++++++++++++++--------------------------- src/lib9/fmt/fmtdef.h | 6 +- src/lib9/fmt/fmtlock.c | 14 +---- src/lib9/fmtlock2.c | 22 ++----- 4 files changed, 83 insertions(+), 124 deletions(-) (limited to 'src') diff --git a/src/lib9/fmt/fmt.c b/src/lib9/fmt/fmt.c index 9c3f45d3..a86482c3 100644 --- a/src/lib9/fmt/fmt.c +++ b/src/lib9/fmt/fmt.c @@ -1,102 +1,107 @@ /* Copyright (c) 2002-2006 Lucent Technologies; see LICENSE */ #include #include +#include #include "plan9.h" #include "fmt.h" #include "fmtdef.h" enum { - Maxfmt = 64 + Maxfmt = 128 }; typedef struct Convfmt Convfmt; struct Convfmt { int c; - volatile Fmts fmt; /* for spin lock in fmtfmt; avoids race due to write order */ + Fmts fmt; }; static struct { - /* lock by calling __fmtlock, __fmtunlock */ - int nfmt; + /* + * lock updates to fmt by calling __fmtlock, __fmtunlock. + * reads can start at nfmt and work backward without + * further locking. later fmtinstalls take priority over earlier + * ones because of the backwards loop. + * once installed, a format is never overwritten. + */ + _Atomic int nfmt; Convfmt fmt[Maxfmt]; -} fmtalloc; - -static Convfmt knownfmt[] = { - ' ', __flagfmt, - '#', __flagfmt, - '%', __percentfmt, - '\'', __flagfmt, - '+', __flagfmt, - ',', __flagfmt, - '-', __flagfmt, - 'C', __runefmt, /* Plan 9 addition */ - 'E', __efgfmt, -#ifndef PLAN9PORT - 'F', __efgfmt, /* ANSI only */ -#endif - 'G', __efgfmt, -#ifndef PLAN9PORT - 'L', __flagfmt, /* ANSI only */ -#endif - 'S', __runesfmt, /* Plan 9 addition */ - 'X', __ifmt, - 'b', __ifmt, /* Plan 9 addition */ - 'c', __charfmt, - 'd', __ifmt, - 'e', __efgfmt, - 'f', __efgfmt, - 'g', __efgfmt, - 'h', __flagfmt, -#ifndef PLAN9PORT - 'i', __ifmt, /* ANSI only */ -#endif - 'l', __flagfmt, - 'n', __countfmt, - 'o', __ifmt, - 'p', __ifmt, - 'r', __errfmt, - 's', __strfmt, -#ifdef PLAN9PORT - 'u', __flagfmt, -#else - 'u', __ifmt, -#endif - 'x', __ifmt, - 0, nil, +} fmtalloc = { + #ifdef PLAN9PORT + ATOMIC_VAR_INIT(27), + #else + ATOMIC_VAR_INIT(30), + #endif + { + {' ', __flagfmt}, + {'#', __flagfmt}, + {'%', __percentfmt}, + {'\'', __flagfmt}, + {'+', __flagfmt}, + {',', __flagfmt}, + {'-', __flagfmt}, + {'C', __runefmt}, /* Plan 9 addition */ + {'E', __efgfmt}, + #ifndef PLAN9PORT + {'F', __efgfmt}, /* ANSI only */ + #endif + {'G', __efgfmt}, + #ifndef PLAN9PORT + {'L', __flagfmt}, /* ANSI only */ + #endif + {'S', __runesfmt}, /* Plan 9 addition */ + {'X', __ifmt}, + {'b', __ifmt}, /* Plan 9 addition */ + {'c', __charfmt}, + {'d', __ifmt}, + {'e', __efgfmt}, + {'f', __efgfmt}, + {'g', __efgfmt}, + {'h', __flagfmt}, + #ifndef PLAN9PORT + {'i', __ifmt}, /* ANSI only */ + #endif + {'l', __flagfmt}, + {'n', __countfmt}, + {'o', __ifmt}, + {'p', __ifmt}, + {'r', __errfmt}, + {'s', __strfmt}, + #ifdef PLAN9PORT + {'u', __flagfmt}, + #else + {'u', __ifmt}, + #endif + {'x', __ifmt}, + } }; - int (*fmtdoquote)(int); /* - * __fmtwlock() must be set + * __fmtlock() must be set */ static int __fmtinstall(int c, Fmts f) { - Convfmt *p, *ep; + Convfmt *p; + int i; if(c<=0 || c>=65536) return -1; if(!f) f = __badfmt; - ep = &fmtalloc.fmt[fmtalloc.nfmt]; - for(p=fmtalloc.fmt; pc == c) - break; - - if(p == &fmtalloc.fmt[Maxfmt]) + i = atomic_load(&fmtalloc.nfmt); + if(i == Maxfmt) return -1; - + p = &fmtalloc.fmt[i]; + p->c = c; p->fmt = f; - if(p == ep){ /* installing a new format character */ - fmtalloc.nfmt++; - p->c = c; - } + atomic_store(&fmtalloc.nfmt, i+1); return 0; } @@ -106,43 +111,21 @@ fmtinstall(int c, int (*f)(Fmt*)) { int ret; - __fmtwlock(); + __fmtlock(); ret = __fmtinstall(c, f); - __fmtwunlock(); + __fmtunlock(); return ret; } static Fmts fmtfmt(int c) { - Convfmt *p, *ep, *kp; - - /* conflict-free check - common case */ - __fmtrlock(); - ep = &fmtalloc.fmt[fmtalloc.nfmt]; - for(p=fmtalloc.fmt; pc == c){ - __fmtrunlock(); + Convfmt *p, *ep; + + ep = &fmtalloc.fmt[atomic_load(&fmtalloc.nfmt)]; + for(p=ep; p-- > fmtalloc.fmt; ) + if(p->c == c) return p->fmt; - } - __fmtrunlock(); - - /* is this a predefined format char? */ - for(kp=knownfmt; kp->c; kp++){ - if(kp->c == c){ - __fmtwlock(); - /* double-check fmtinstall didn't happen */ - for(p=fmtalloc.fmt; pc == c){ - __fmtwunlock(); - return p->fmt; - } - } - __fmtinstall(kp->c, kp->fmt); - __fmtwunlock(); - return kp->fmt; - } - } return __badfmt; } diff --git a/src/lib9/fmt/fmtdef.h b/src/lib9/fmt/fmtdef.h index d547184d..2bafd36d 100644 --- a/src/lib9/fmt/fmtdef.h +++ b/src/lib9/fmt/fmtdef.h @@ -36,10 +36,8 @@ void * __fmtflush(Fmt *f, void *t, int len); int __fmtpad(Fmt *f, int n); double __fmtpow10(int n); int __fmtrcpy(Fmt *f, const void *vm, int n); -void __fmtrlock(void); -void __fmtrunlock(void); -void __fmtwlock(void); -void __fmtwunlock(void); +void __fmtlock(void); +void __fmtunlock(void); int __ifmt(Fmt *f); int __isInf(double d, int sign); int __isNaN(double d); diff --git a/src/lib9/fmt/fmtlock.c b/src/lib9/fmt/fmtlock.c index eb9cd845..cabe05f4 100644 --- a/src/lib9/fmt/fmtlock.c +++ b/src/lib9/fmt/fmtlock.c @@ -5,21 +5,11 @@ #include "fmtdef.h" void -__fmtrlock(void) +__fmtlock(void) { } void -__fmtrunlock(void) -{ -} - -void -__fmtwlock(void) -{ -} - -void -__fmtwunlock(void) +__fmtunlock(void) { } diff --git a/src/lib9/fmtlock2.c b/src/lib9/fmtlock2.c index b755daa3..d711e6d4 100644 --- a/src/lib9/fmtlock2.c +++ b/src/lib9/fmtlock2.c @@ -1,28 +1,16 @@ #include #include -static RWLock fmtlock; +static Lock fmtlock; void -__fmtrlock(void) +__fmtlock(void) { - rlock(&fmtlock); + lock(&fmtlock); } void -__fmtrunlock(void) +__fmtunlock(void) { - runlock(&fmtlock); -} - -void -__fmtwlock(void) -{ - wlock(&fmtlock); -} - -void -__fmtwunlock(void) -{ - wunlock(&fmtlock); + unlock(&fmtlock); } -- cgit v1.2.3