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/****************************************************************************
**
** This file is part of GAP, a system for computational discrete algebra.
**
** Copyright of GAP belongs to its developers, whose names are too numerous
** to list here. Please refer to the COPYRIGHT file for details.
**
** SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "symbols.h"
#include "error.h"
#include "plist.h"
#include "stringobj.h"
#include "sysstr.h"
#ifdef HPCGAP
#include "hpc/tls.h"
#include "hpc/thread.h"
#endif
void InitSymbolTableKernel(SymbolTable * symtab,
const char * cookieCount,
const char * cookieTable,
SymbolIdToNameFunc nameFunc,
NewSymbolFunc newSymbolFunc)
{
GAP_ASSERT(symtab);
GAP_ASSERT(cookieCount);
GAP_ASSERT(cookieTable);
GAP_ASSERT(nameFunc);
GAP_ASSERT(newSymbolFunc);
symtab->count = INTOBJ_INT(0);
symtab->table = 0;
symtab->nameFunc = nameFunc;
symtab->newSymbolFunc = newSymbolFunc;
#ifdef HPCGAP
pthread_rwlock_init(&symtab->lock, NULL);
symtab->lockOwner = 0;
symtab->lockDepth = 0;
#endif
InitGlobalBag(&symtab->count, cookieCount);
InitGlobalBag(&symtab->table, cookieTable);
}
void InitSymbolTableLibrary(SymbolTable * symtab, UInt initialSize)
{
GAP_ASSERT(symtab);
symtab->table = NEW_PLIST(T_PLIST, initialSize);
SET_LEN_PLIST(symtab->table, initialSize);
#ifdef HPCGAP
MakeBagPublic(symtab->table);
#endif
}
#ifdef HPCGAP
void LockSymbolTableForReading(SymbolTable * symtab)
{
if (PreThreadCreation)
return;
if (symtab->lockOwner == GetTLS()) {
symtab->lockDepth++;
return;
}
pthread_rwlock_rdlock(&symtab->lock);
}
void LockSymbolTableForWriting(SymbolTable * symtab)
{
if (PreThreadCreation)
return;
if (symtab->lockOwner == GetTLS()) {
symtab->lockDepth++;
return;
}
pthread_rwlock_wrlock(&symtab->lock);
symtab->lockOwner = GetTLS();
symtab->lockDepth = 1;
}
void UnlockSymbolTable(SymbolTable * symtab)
{
if (PreThreadCreation)
return;
if (symtab->lockOwner == GetTLS()) {
symtab->lockDepth--;
if (symtab->lockDepth != 0)
return;
symtab->lockOwner = NULL;
}
pthread_rwlock_unlock(&symtab->lock);
}
#endif
int LengthSymbolTable(SymbolTable * symtab)
{
#ifdef HPCGAP
LockSymbolTableForReading(symtab);
#endif
int count = INT_INTOBJ(symtab->count);
#ifdef HPCGAP
UnlockSymbolTable(symtab);
#endif
return count;
}
static inline UInt HashString(const Char * name)
{
UInt hash = 0;
while (*name) {
hash = 65599 * hash + *name++;
}
return hash;
}
UInt LookupSymbol(SymbolTable * symtab, const char * name)
{
Obj id; // symbol id (as imm intobj)
UInt pos; // hash position
Char namx[1024]; // temporary copy of <name>
Obj string; // temporary string object <name>
Obj table; // temporary copy of <symtab->table>
UInt i; // loop variable
UInt sizeTable;
if (strlen(name) > 1023) {
// Note: We can't pass 'name' here, as it might get moved by garbage
// collection
ErrorQuit("Symbol names must consist of at most 1023 characters", 0,
0);
}
// start looking in the table at the following hash position
const UInt hash = HashString(name);
#ifdef HPCGAP
LockSymbolTableForReading(symtab); // try a read lock first
#endif
// look through the table until we find a free slot or the global
sizeTable = LEN_PLIST(symtab->table);
pos = (hash % sizeTable) + 1;
while (
(id = ELM_PLIST(symtab->table, pos)) != 0 &&
strcmp(CONST_CSTR_STRING(symtab->nameFunc(INT_INTOBJ(id))), name)) {
pos = (pos % sizeTable) + 1;
}
if (id != 0) {
#ifdef HPCGAP
UnlockSymbolTable(symtab);
#endif
return INT_INTOBJ(id);
}
#ifdef HPCGAP
if (!PreThreadCreation) {
// switch to a write lock
UnlockSymbolTable(symtab);
LockSymbolTableForWriting(symtab);
// when we switched to a write lock, another thread might have
// modified the symbol table; so repeat the lookup
sizeTable = LEN_PLIST(symtab->table);
pos = (hash % sizeTable) + 1;
while ((id = ELM_PLIST(symtab->table, pos)) != 0 &&
strcmp(CONST_CSTR_STRING(symtab->nameFunc(INT_INTOBJ(id))),
name)) {
pos = (pos % sizeTable) + 1;
}
if (id != 0) {
UnlockSymbolTable(symtab);
return INT_INTOBJ(id);
}
}
#endif
// if we did not find the global variable, make a new one and enter it
// (copy the name first, to avoid a stale pointer in case of a GC)
strxcpy(namx, name, sizeof(namx));
string = MakeImmString(namx);
// store the id
GAP_ASSERT(id == 0);
symtab->count = id = INTOBJ_INT(INT_INTOBJ(symtab->count) + 1);
SET_ELM_PLIST(symtab->table, pos, id);
// notify about the new entry
symtab->newSymbolFunc(symtab, INT_INTOBJ(id), string);
// if the table is too crowded, make a larger one, rehash the names
if (sizeTable < 3 * INT_INTOBJ(id) / 2) {
table = symtab->table;
sizeTable = 2 * sizeTable + 1;
symtab->table = NEW_PLIST(T_PLIST, sizeTable);
SET_LEN_PLIST(symtab->table, sizeTable);
#ifdef HPCGAP
// The list is briefly non-public, but this is safe, because
// the mutex protects it from being accessed by other threads.
MakeBagPublic(symtab->table);
#endif
for (i = 1; i <= (sizeTable - 1) / 2; i++) {
Obj id2 = ELM_PLIST(table, i);
if (id2 == 0)
continue;
string = symtab->nameFunc(INT_INTOBJ(id2));
pos = HashString(CONST_CSTR_STRING(string));
pos = (pos % sizeTable) + 1;
while (ELM_PLIST(symtab->table, pos) != 0) {
pos = (pos % sizeTable) + 1;
}
SET_ELM_PLIST(symtab->table, pos, id2);
}
}
#ifdef HPCGAP
UnlockSymbolTable(symtab);
#endif
// return the symbol id
return INT_INTOBJ(id);
}
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