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Switch to using unique_ptr in env_node_t

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Makes our memory management of the variable stack more explicit
This commit is contained in:
ridiculousfish 2017-01-26 12:40:55 -08:00
parent 8e577b01bc
commit 59a3968fd2
1 changed files with 43 additions and 46 deletions
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89
src/env.cpp
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@ -75,7 +75,6 @@ static const wchar_t *const curses_variable[] = {L"TERM", L"TERMINFO", L"TERMINF
class env_node_t {
friend struct var_stack_t;
env_node_t(bool is_new_scope) : new_scope(is_new_scope) {}
~env_node_t() {}
public:
@ -88,7 +87,7 @@ public:
/// Does this node contain any variables which are exported to subshells.
bool exportv = false;
/// Pointer to next level.
env_node_t *next = NULL;
std::unique_ptr<env_node_t> next;
/// Returns a pointer to the given entry if present, or NULL.
const var_entry_t *find_entry(const wcstring &key);
@ -100,7 +99,7 @@ class variable_entry_t {
static pthread_mutex_t env_lock = PTHREAD_MUTEX_INITIALIZER;
static int local_scope_exports(env_node_t *n);
static bool local_scope_exports(const env_node_t *n);
static void handle_locale(const wchar_t *env_var_name);
// A class wrapping up a variable stack
@ -109,9 +108,10 @@ static void handle_locale(const wchar_t *env_var_name);
// if we introduce multiple threads of execution
struct var_stack_t {
// Top node on the function stack.
env_node_t *top = NULL;
std::unique_ptr<env_node_t> top = NULL;
// Bottom node on the function stack.
// Bottom node on the function stack
// This is an observer pointer
env_node_t *global_env = NULL;
// Exported variable array used by execv.
@ -122,17 +122,8 @@ struct var_stack_t {
void mark_changed_exported() { has_changed_exported = true; }
void update_export_array_if_necessary();
var_stack_t() {
this->top = new env_node_t(false);
this->global_env = this->top;
}
~var_stack_t() {
while (this->top) {
env_node_t *next = this->top->next;
delete this->top;
this->top = next;
}
var_stack_t() : top(new env_node_t(false)) {
this->global_env = this->top.get();
}
// Pushes a new node onto our stack
@ -154,50 +145,55 @@ struct var_stack_t {
};
void var_stack_t::push(bool new_scope) {
env_node_t *node = new env_node_t(new_scope);
node->next = this->top;
this->top = node;
if (new_scope && local_scope_exports(this->top)) {
std::unique_ptr<env_node_t> node(new env_node_t(new_scope));
node->next = std::move(this->top);
this->top = std::move(node);
if (new_scope && local_scope_exports(this->top.get())) {
this->mark_changed_exported();
}
}
void var_stack_t::pop() {
// Don't pop the global
if (this->top == this->global_env) {
if (this->top.get() == this->global_env) {
debug(0, _(L"Tried to pop empty environment stack."));
sanity_lose();
return;
}
const wchar_t *locale_changed = NULL;
env_node_t *killme = this->top;
for (int i = 0; locale_variable[i]; i++) {
var_table_t::iterator result = killme->env.find(locale_variable[i]);
if (result != killme->env.end()) {
var_table_t::iterator result = top->env.find(locale_variable[i]);
if (result != top->env.end()) {
locale_changed = locale_variable[i];
break;
}
}
if (killme->new_scope) { //!OCLINT(collapsible if statements)
if (killme->exportv || local_scope_exports(killme->next)) {
if (top->new_scope) { //!OCLINT(collapsible if statements)
if (top->exportv || local_scope_exports(top->next.get())) {
this->mark_changed_exported();
}
}
this->top = this->top->next;
// Actually do the pop!
// Move the top pointer into a local variable, then replace the top pointer with the next pointer
// afterwards we should have a node with no next pointer, and our top should be non-null
std::unique_ptr<env_node_t> old_top = std::move(this->top);
this->top = std::move(old_top->next);
old_top->next.reset();
assert(this->top && old_top && !old_top->next);
assert(this->top != NULL);
var_table_t::iterator iter;
for (iter = killme->env.begin(); iter != killme->env.end(); ++iter) {
const var_entry_t &entry = iter->second;
for (const auto &entry_pair : old_top->env) {
const var_entry_t &entry = entry_pair.second;
if (entry.exportv) {
this->mark_changed_exported();
break;
}
}
delete killme;
// TODO: move this to something general
if (locale_changed) handle_locale(locale_changed);
}
@ -207,7 +203,7 @@ const env_node_t *var_stack_t::next_scope_to_search(const env_node_t *node) cons
if (node == this->global_env) {
return NULL;
}
return node->new_scope ? this->global_env : node->next;
return node->new_scope ? this->global_env : node->next.get();
}
env_node_t *var_stack_t::next_scope_to_search(env_node_t *node) {
@ -215,13 +211,13 @@ env_node_t *var_stack_t::next_scope_to_search(env_node_t *node) {
if (node == this->global_env) {
return NULL;
}
return node->new_scope ? this->global_env : node->next;
return node->new_scope ? this->global_env : node->next.get();
}
env_node_t *var_stack_t::resolve_unspecified_scope() {
env_node_t *node = this->top;
env_node_t *node = this->top.get();
while (node && !node->new_scope) {
node = node->next;
node = node->next.get();
}
return node ? node : this->global_env;
}
@ -637,7 +633,7 @@ void env_init(const struct config_paths_t *paths /* or NULL */) {
/// Search all visible scopes in order for the specified key. Return the first scope in which it was
/// found.
static env_node_t *env_get_node(const wcstring &key) {
env_node_t *env = vars_stack().top;
env_node_t *env = vars_stack().top.get();
while (env != NULL) {
if (env->find_entry(key) != NULL) {
break;
@ -750,7 +746,7 @@ int env_set(const wcstring &key, const wchar_t *val, env_mode_flags_t var_mode)
if (var_mode & ENV_GLOBAL) {
node = vars_stack().global_env;
} else if (var_mode & ENV_LOCAL) {
node = vars_stack().top;
node = vars_stack().top.get();
} else if (preexisting_node != NULL) {
node = preexisting_node;
if ((var_mode & (ENV_EXPORT | ENV_UNEXPORT)) == 0) {
@ -845,7 +841,7 @@ static bool try_remove(env_node_t *n, const wchar_t *key, int var_mode) {
if (n->new_scope) {
return try_remove(vars_stack().global_env, key, var_mode);
}
return try_remove(n->next, key, var_mode);
return try_remove(n->next.get(), key, var_mode);
}
int env_remove(const wcstring &key, int var_mode) {
@ -857,7 +853,7 @@ int env_remove(const wcstring &key, int var_mode) {
return 2;
}
first_node = vars_stack().top;
first_node = vars_stack().top.get();
if (!(var_mode & ENV_UNIVERSAL)) {
if (var_mode & ENV_GLOBAL) {
@ -940,7 +936,7 @@ env_var_t env_get_string(const wcstring &key, env_mode_flags_t mode) {
/* Lock around a local region */
scoped_lock locker(env_lock);
env_node_t *env = search_local ? vars_stack().top : vars_stack().global_env;
env_node_t *env = search_local ? vars_stack().top.get() : vars_stack().global_env;
while (env != NULL) {
const var_entry_t *entry = env->find_entry(key);
@ -1001,7 +997,7 @@ bool env_exist(const wchar_t *key, env_mode_flags_t mode) {
}
if (test_local || test_global) {
const env_node_t *env = test_local ? vars_stack().top : vars_stack().global_env;
const env_node_t *env = test_local ? vars_stack().top.get() : vars_stack().global_env;
while (env != NULL) {
if (env == vars_stack().global_env && !test_global) {
break;
@ -1032,14 +1028,15 @@ bool env_exist(const wchar_t *key, env_mode_flags_t mode) {
/// Returns true if the specified scope or any non-shadowed non-global subscopes contain an exported
/// variable.
static int local_scope_exports(env_node_t *n) {
static bool local_scope_exports(const env_node_t *n) {
assert(n != NULL);
if (n == vars_stack().global_env) return 0;
if (n->exportv) return 1;
if (n->new_scope) return 0;
return local_scope_exports(n->next);
return local_scope_exports(n->next.get());
}
void env_push(bool new_scope) {
@ -1073,7 +1070,7 @@ wcstring_list_t env_get_names(int flags) {
int show_global = flags & ENV_GLOBAL;
int show_universal = flags & ENV_UNIVERSAL;
env_node_t *n = vars_stack().top;
const env_node_t *n = vars_stack().top.get();
const bool show_exported = (flags & ENV_EXPORT) || !(flags & ENV_UNEXPORT);
const bool show_unexported = (flags & ENV_UNEXPORT) || !(flags & ENV_EXPORT);
@ -1089,7 +1086,7 @@ wcstring_list_t env_get_names(int flags) {
if (n->new_scope)
break;
else
n = n->next;
n = n->next.get();
}
}
@ -1116,7 +1113,7 @@ static void get_exported(const env_node_t *n, std::map<wcstring, wcstring> *h) {
if (n->new_scope)
get_exported(vars_stack().global_env, h);
else
get_exported(n->next, h);
get_exported(n->next.get(), h);
var_table_t::const_iterator iter;
for (iter = n->env.begin(); iter != n->env.end(); ++iter) {
@ -1171,7 +1168,7 @@ void var_stack_t::update_export_array_if_necessary() {
debug(4, L"env_export_arr() recalc");
get_exported(this->top, &vals);
get_exported(this->top.get(), &vals);
if (uvars()) {
const wcstring_list_t uni = uvars()->get_names(true, false);