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Merge pull request #5865 from pennae/memory-friendliness

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be more memory friendly
This commit is contained in:
Eelco Dolstra 2022-03-11 11:52:39 +01:00 committed by GitHub
parent 167766b65c 4d629c4f7a
commit 31a392dfe2
7 changed files with 107 additions and 69 deletions
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91
src/libexpr/eval-inline.hh
View file

@ -24,6 +24,81 @@ LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const char * s, const
}
/* Note: Various places expect the allocated memory to be zeroed. */
[[gnu::always_inline]]
inline void * allocBytes(size_t n)
{
void * p;
#if HAVE_BOEHMGC
p = GC_MALLOC(n);
#else
p = calloc(n, 1);
#endif
if (!p) throw std::bad_alloc();
return p;
}
[[gnu::always_inline]]
Value * EvalState::allocValue()
{
#if HAVE_BOEHMGC
/* We use the boehm batch allocator to speed up allocations of Values (of which there are many).
GC_malloc_many returns a linked list of objects of the given size, where the first word
of each object is also the pointer to the next object in the list. This also means that we
have to explicitly clear the first word of every object we take. */
if (!*valueAllocCache) {
*valueAllocCache = GC_malloc_many(sizeof(Value));
if (!*valueAllocCache) throw std::bad_alloc();
}
/* GC_NEXT is a convenience macro for accessing the first word of an object.
Take the first list item, advance the list to the next item, and clear the next pointer. */
void * p = *valueAllocCache;
*valueAllocCache = GC_NEXT(p);
GC_NEXT(p) = nullptr;
#else
void * p = allocBytes(sizeof(Value));
#endif
nrValues++;
return (Value *) p;
}
[[gnu::always_inline]]
Env & EvalState::allocEnv(size_t size)
{
nrEnvs++;
nrValuesInEnvs += size;
Env * env;
#if HAVE_BOEHMGC
if (size == 1) {
/* see allocValue for explanations. */
if (!*env1AllocCache) {
*env1AllocCache = GC_malloc_many(sizeof(Env) + sizeof(Value *));
if (!*env1AllocCache) throw std::bad_alloc();
}
void * p = *env1AllocCache;
*env1AllocCache = GC_NEXT(p);
GC_NEXT(p) = nullptr;
env = (Env *) p;
} else
#endif
env = (Env *) allocBytes(sizeof(Env) + size * sizeof(Value *));
env->type = Env::Plain;
/* We assume that env->values has been cleared by the allocator; maybeThunk() and lookupVar fromWith expect this. */
return *env;
}
[[gnu::always_inline]]
void EvalState::forceValue(Value & v, const Pos & pos)
{
forceValue(v, [&]() { return pos; });
@ -52,6 +127,7 @@ void EvalState::forceValue(Value & v, Callable getPos)
}
[[gnu::always_inline]]
inline void EvalState::forceAttrs(Value & v, const Pos & pos)
{
forceAttrs(v, [&]() { return pos; });
@ -59,6 +135,7 @@ inline void EvalState::forceAttrs(Value & v, const Pos & pos)
template <typename Callable>
[[gnu::always_inline]]
inline void EvalState::forceAttrs(Value & v, Callable getPos)
{
forceValue(v, getPos);
@ -67,6 +144,7 @@ inline void EvalState::forceAttrs(Value & v, Callable getPos)
}
[[gnu::always_inline]]
inline void EvalState::forceList(Value & v, const Pos & pos)
{
forceValue(v, pos);
@ -74,18 +152,5 @@ inline void EvalState::forceList(Value & v, const Pos & pos)
throwTypeError(pos, "value is %1% while a list was expected", v);
}
/* Note: Various places expect the allocated memory to be zeroed. */
inline void * allocBytes(size_t n)
{
void * p;
#if HAVE_BOEHMGC
p = GC_MALLOC(n);
#else
p = calloc(n, 1);
#endif
if (!p) throw std::bad_alloc();
return p;
}
}

38
src/libexpr/eval.cc
View file

@ -449,8 +449,10 @@ EvalState::EvalState(
, regexCache(makeRegexCache())
#if HAVE_BOEHMGC
, valueAllocCache(std::allocate_shared<void *>(traceable_allocator<void *>(), nullptr))
, env1AllocCache(std::allocate_shared<void *>(traceable_allocator<void *>(), nullptr))
#else
, valueAllocCache(std::make_shared<void *>(nullptr))
, env1AllocCache(std::make_shared<void *>(nullptr))
#endif
, baseEnv(allocEnv(128))
, staticBaseEnv(false, 0)
@ -876,42 +878,6 @@ inline Value * EvalState::lookupVar(Env * env, const ExprVar & var, bool noEval)
}
Value * EvalState::allocValue()
{
/* We use the boehm batch allocator to speed up allocations of Values (of which there are many).
GC_malloc_many returns a linked list of objects of the given size, where the first word
of each object is also the pointer to the next object in the list. This also means that we
have to explicitly clear the first word of every object we take. */
if (!*valueAllocCache) {
*valueAllocCache = GC_malloc_many(sizeof(Value));
if (!*valueAllocCache) throw std::bad_alloc();
}
/* GC_NEXT is a convenience macro for accessing the first word of an object.
Take the first list item, advance the list to the next item, and clear the next pointer. */
void * p = *valueAllocCache;
GC_PTR_STORE_AND_DIRTY(&*valueAllocCache, GC_NEXT(p));
GC_NEXT(p) = nullptr;
nrValues++;
auto v = (Value *) p;
return v;
}
Env & EvalState::allocEnv(size_t size)
{
nrEnvs++;
nrValuesInEnvs += size;
Env * env = (Env *) allocBytes(sizeof(Env) + size * sizeof(Value *));
env->type = Env::Plain;
/* We assume that env->values has been cleared by the allocator; maybeThunk() and lookupVar fromWith expect this. */
return *env;
}
void EvalState::mkList(Value & v, size_t size)
{
v.mkList(size);

11
src/libexpr/eval.hh
View file

@ -133,9 +133,14 @@ private:
/* Cache used by prim_match(). */
std::shared_ptr<RegexCache> regexCache;
#if HAVE_BOEHMGC
/* Allocation cache for GC'd Value objects. */
std::shared_ptr<void *> valueAllocCache;
/* Allocation cache for size-1 Env objects. */
std::shared_ptr<void *> env1AllocCache;
#endif
public:
EvalState(
@ -347,8 +352,8 @@ public:
void autoCallFunction(Bindings & args, Value & fun, Value & res);
/* Allocation primitives. */
Value * allocValue();
Env & allocEnv(size_t size);
inline Value * allocValue();
inline Env & allocEnv(size_t size);
Value * allocAttr(Value & vAttrs, const Symbol & name);
Value * allocAttr(Value & vAttrs, std::string_view name);
@ -509,3 +514,5 @@ extern EvalSettings evalSettings;
static const std::string corepkgsPrefix{"/__corepkgs__/"};
}
#include "eval-inline.hh"

13
src/libexpr/nixexpr.hh
View file

@ -23,14 +23,13 @@ MakeError(RestrictedPathError, Error);
struct Pos
{
FileOrigin origin;
Symbol file;
unsigned int line, column;
Pos() : origin(foString), line(0), column(0) { }
Pos(FileOrigin origin, const Symbol & file, unsigned int line, unsigned int column)
: origin(origin), file(file), line(line), column(column) { }
uint32_t line;
FileOrigin origin:2;
uint32_t column:30;
Pos() : line(0), origin(foString), column(0) { };
Pos(FileOrigin origin, const Symbol & file, uint32_t line, uint32_t column)
: file(file), line(line), origin(origin), column(column) { };
operator bool() const
{
return line != 0;

1
src/libutil/error.hh
View file

@ -54,6 +54,7 @@ typedef enum {
lvlVomit
} Verbosity;
/* adjust Pos::origin bit width when adding stuff here */
typedef enum {
foFile,
foStdin,

7
src/libutil/finally.hh
View file

@ -1,14 +1,13 @@
#pragma once
#include <functional>
/* A trivial class to run a function at the end of a scope. */
template<typename Fn>
class Finally
{
private:
std::function<void()> fun;
Fn fun;
public:
Finally(std::function<void()> fun) : fun(fun) { }
Finally(Fn fun) : fun(std::move(fun)) { }
~Finally() { fun(); }
};

15
src/libutil/util.cc
View file

@ -682,7 +682,14 @@ std::string drainFD(int fd, bool block, const size_t reserveSize)
void drainFD(int fd, Sink & sink, bool block)
{
int saved;
// silence GCC maybe-uninitialized warning in finally
int saved = 0;
if (!block) {
saved = fcntl(fd, F_GETFL);
if (fcntl(fd, F_SETFL, saved | O_NONBLOCK) == -1)
throw SysError("making file descriptor non-blocking");
}
Finally finally([&]() {
if (!block) {
@ -691,12 +698,6 @@ void drainFD(int fd, Sink & sink, bool block)
}
});
if (!block) {
saved = fcntl(fd, F_GETFL);
if (fcntl(fd, F_SETFL, saved | O_NONBLOCK) == -1)
throw SysError("making file descriptor non-blocking");
}
std::vector<unsigned char> buf(64 * 1024);
while (1) {
checkInterrupt();