daScript/src/misc/gc_node.cpp at master · WhyNot135/daScript · GitHub

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#include "daScript/misc/platform.h"

#include "daScript/misc/gc_node.h"

#include "daScript/misc/crash_handler.h"

#include <inttypes.h>

#include <stdlib.h>

namespace das {

// debugging id - to break on

static uint64_t gc_break_on_id = 0;

// installed by the AST layer (ast_gc_report.cpp); see gc_node.h

DAS_API gc_describe_fn gc_node_describe_hook = nullptr;

// ---- gc_root statics ----

static thread_local gc_root s_gc_thread_root;

static thread_local gc_root * s_gc_active_root = &s_gc_thread_root;

std::atomic<uint64_t> gc_root::gc_next_id { 1 };

static void gc_check_break ( uint64_t id );

gc_root & gc_root::gc_get_thread_root() {

return s_gc_thread_root;

}

gc_root * & gc_root::gc_get_active_root() {

return s_gc_active_root;

}

// ---- gc_root ----

gc_root::~gc_root() {

if ( gc_first ) {

gc_sweep();

}

void gc_root::gc_link ( gc_node * node ) {

DAS_ASSERT(node && "gc_link: null node");

DAS_ASSERT(node->gc_owner == nullptr && "gc_link: node already on a root");

// gc_check_break(node->gc_id);

node->gc_owner = this;

node->gc_prev = gc_last;

node->gc_next = nullptr;

if ( gc_last ) {

gc_last->gc_next = node;

} else {

gc_first = node;

}

gc_last = node;

gc_count++;

}

void gc_root::gc_unlink ( gc_node * node ) {

DAS_ASSERT(node && "gc_unlink: null node");

DAS_ASSERT(node->gc_owner == this && "gc_unlink: node not on this root");

// gc_check_break(node->gc_id);

if ( node->gc_prev ) {

node->gc_prev->gc_next = node->gc_next;

} else {

gc_first = node->gc_next;

}

if ( node->gc_next ) {

node->gc_next->gc_prev = node->gc_prev;

} else {

gc_last = node->gc_prev;

}

node->gc_prev = nullptr;

node->gc_next = nullptr;

node->gc_owner = nullptr;

DAS_ASSERT(gc_count > 0);

gc_count--;

}

void gc_root::gc_sweep() {

gc_collecting = true;

while ( gc_first ) {

auto node = gc_first;

gc_unlink(node);

uint32_t swept_magic = GC_MAGIC_SWEPT_PREFIX | (node->gc_magic & 0xFFFFu);

#if DAS_GC_DEBUG

// !!! DO NOT REMOVE !!!

// Memory poisoning mode for debugging use-after-sweep.

// Destroys the object but keeps memory allocated with 0xCD fill.

// gc_magic (with type tag) and gc_id are restored so crashed nodes can be identified.

// Set DAS_GC_DEBUG=1 to enable, then use DAS_GC_BREAK_ON_ID to find the creator.

{

uint64_t saved_id = node->gc_id;

node->~gc_node();

#ifdef _MSC_VER

auto sz = _msize(node);

#elif defined(__APPLE__)

auto sz = malloc_size(node);

#else

auto sz = malloc_usable_size(node);

#endif

memset(node, 0xCD, sz);

node->gc_magic = swept_magic;

node->gc_id = saved_id;

}

#else

node->gc_magic = swept_magic;

delete node;

#endif

}

gc_collecting = false;

}

void gc_root::gc_dump_to_thread_root() {

auto & threadRoot = gc_get_thread_root();

while ( gc_first ) {

auto node = gc_first;

gc_unlink(node);

threadRoot.gc_link(node);

}

void gc_root::gc_report() const {

DAS_FATAL_LOG("gc_root %p: count=%" PRIu64 "\n", (const void *)this, gc_count);

char atbuf[256];

auto node = gc_first;

while ( node ) {

atbuf[0] = 0;

if ( gc_node_describe_hook ) gc_node_describe_hook(node, atbuf, (int)sizeof(atbuf));

DAS_FATAL_LOG(" node %p: id=%" PRIu64 " type=%s magic=0x%08x %s\n",

(const void *)node, node->gc_id, node->gc_type_name(), node->gc_magic, atbuf);

node = node->gc_next;

}

// ---- gc_node debug break ----

// Set gc_break_on_id via debugger or env DAS_GC_BREAK_ON_ID to break

// when a specific gc_id is assigned. Useful for tracing where a leaked node was born.

static uint64_t gc_init_break_on_id() {

if ( auto env = getenv("DAS_GC_BREAK_ON_ID") ) {

return strtoull(env, nullptr, 0);

}

return 0;

}

static void gc_check_break ( uint64_t id ) {

if ( gc_break_on_id == 0 ) {

static bool once = true;

if ( once ) { once = false; gc_break_on_id = gc_init_break_on_id(); }

}

if ( gc_break_on_id && id == gc_break_on_id ) {

DAS_FATAL_LOG("gc_node break: id=%" PRIu64 "\n", id);

print_current_stack_trace();

os_debug_break();

}

// ---- gc_node ----

gc_node::gc_node() {

gc_id = gc_root::gc_next_id.fetch_add(1, std::memory_order_relaxed);

gc_check_break(gc_id);

gc_root::gc_get_active_root()->gc_link(this);

}

gc_node::gc_node ( const gc_node & ) {

// New node with new ID, linked to the active root. Does NOT copy list position.

gc_id = gc_root::gc_next_id.fetch_add(1, std::memory_order_relaxed);

gc_check_break(gc_id);

gc_root::gc_get_active_root()->gc_link(this);

}

gc_node::gc_node ( gc_node && src ) {

// Take over source's list position

gc_magic = src.gc_magic;

gc_id = src.gc_id;

gc_prev = src.gc_prev;

gc_next = src.gc_next;

gc_owner = src.gc_owner;

// Patch neighbors to point to us

if ( gc_prev ) {

gc_prev->gc_next = this;

} else if ( gc_owner ) {

gc_owner->gc_first = this;

}

if ( gc_next ) {

gc_next->gc_prev = this;

} else if ( gc_owner ) {

gc_owner->gc_last = this;

}

// Detach source

src.gc_prev = nullptr;

src.gc_next = nullptr;

src.gc_owner = nullptr;

src.gc_magic = GC_MAGIC_DEAD;

}

gc_node & gc_node::operator = ( gc_node && src ) {

if ( this == &src ) return *this;

// Unlink self from current root

if ( gc_owner ) {

gc_owner->gc_unlink(this);

}

// Take over source's list position

gc_magic = src.gc_magic;

gc_id = src.gc_id;

gc_prev = src.gc_prev;

gc_next = src.gc_next;

gc_owner = src.gc_owner;

if ( gc_prev ) {

gc_prev->gc_next = this;

} else if ( gc_owner ) {

gc_owner->gc_first = this;

}

if ( gc_next ) {

gc_next->gc_prev = this;

} else if ( gc_owner ) {

gc_owner->gc_last = this;

}

src.gc_prev = nullptr;

src.gc_next = nullptr;

src.gc_owner = nullptr;

src.gc_magic = GC_MAGIC_DEAD;

return *this;

}

gc_node::~gc_node() {

gc_check_break(gc_id);

if ( gc_owner ) {

// Node is being deleted outside of gc_sweep.

// During the migration period, this can happen legitimately when old code

// paths delete TypeDecl. In DAS_GC_DEBUG mode, assert to catch bugs.

#if DAS_GC_DEBUG

if ( !gc_owner->gc_collecting ) {

DAS_FATAL_LOG("gc_node id=%" PRIu64 " deleted outside of gc_sweep\n", gc_id);

DAS_ASSERTF(false, "gc_node id=%" PRIu64 " deleted outside of gc_sweep", gc_id);

}

#endif

gc_owner->gc_unlink(this);

}

if ( gc_is_alive() ) {

gc_magic = GC_MAGIC_DEAD;

}

void gc_node::gc_unlink() {

if ( gc_owner ) {

gc_owner->gc_unlink(this);

}

void gc_node::gc_link ( gc_root * root ) {

DAS_ASSERT(gc_owner == nullptr && "gc_link: already linked");

root->gc_link(this);

}

void gc_node::gc_assign ( gc_root * new_root ) {

if ( gc_owner == new_root ) return;

if ( gc_owner ) {

gc_owner->gc_unlink(this);

}

new_root->gc_link(this);

}

const char * gc_node::gc_type_name() const {

uint16_t tag = gc_magic & 0xFFFFu;

switch ( tag ) {

case GC_TAG_TYPEDECL: return "TypeDecl";

case GC_TAG_EXPRESSION: return "Expression";

case GC_TAG_MAKEFIELDDECL: return "MakeFieldDecl";

case GC_TAG_MAKESTRUCT: return "MakeStruct";

case GC_TAG_FUNCTION: return "Function";

case GC_TAG_ENUMERATION: return "Enumeration";

case GC_TAG_STRUCTURE: return "Structure";

case GC_TAG_VARIABLE: return "Variable";

default: return "gc_node";

}

void gc_node::gc_verify() const {

if ( !gc_is_alive() ) {

const char * typeName = gc_type_name();

if ( (gc_magic & 0xFFFF0000u) == GC_MAGIC_SWEPT_PREFIX ) {

DAS_FATAL_ERROR("%s id=%" PRIu64 " was already swept (use-after-sweep)", typeName, gc_id);

} else if ( gc_magic == GC_MAGIC_DEAD ) {

DAS_FATAL_ERROR("%s id=%" PRIu64 " was already deleted (use-after-free)", typeName, gc_id);

} else {

DAS_FATAL_ERROR("%s id=%" PRIu64 " has corrupt magic=0x%08x", typeName, gc_id, gc_magic);

}

// ---- gc_guard ----

gc_guard::gc_guard() {

saved_thread_root = gc_root::gc_get_active_root();

gc_root::gc_get_active_root() = &guard_root;

}

gc_guard::~gc_guard() {

gc_root::gc_get_active_root() = saved_thread_root;

guard_root.gc_sweep();

}

gc_active_scope::gc_active_scope ( gc_root * use ) {

saved_active = gc_root::gc_get_active_root();

gc_root::gc_get_active_root() = use;

}

gc_active_scope::~gc_active_scope() {

gc_root::gc_get_active_root() = saved_active;

}

daScript/src/misc/gc_node.cpp at master · WhyNot135/daScript · GitHub

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