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LRU cache work

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This commit is contained in:
ridiculousfish 2012-01-25 11:47:45 -08:00
parent e94e1cc72f
commit 8e56763c98
4 changed files with 214 additions and 143 deletions
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134
autoload.cpp
View file

@ -10,6 +10,26 @@ The classes responsible for autoloading functions and completions.
const size_t kLRULimit = 256;
file_access_attempt_t access_file(const wcstring &path, int mode) {
file_access_attempt_t result = {0};
struct stat statbuf;
if (wstat(path.c_str(), &statbuf)) {
result.error = errno;
} else {
result.mod_time = statbuf.st_mtime;
if (waccess(path.c_str(), mode)) {
result.error = errno;
} else {
result.accessible = true;
}
}
// Note that we record the last checked time after the call, on the assumption that in a slow filesystem, the lag comes before the kernel check, not after.
result.stale = false;
result.last_checked = time(NULL);
return result;
}
/** A node in our LRU map */
class file_access_node_t {
public:
@ -77,23 +97,7 @@ file_access_node_t *access_tracker_t::while_locked_find_node(const wcstring &pat
}
file_access_attempt_t access_tracker_t::attempt_access(const wcstring& path) const {
file_access_attempt_t result = {0};
struct stat statbuf;
if (wstat(path.c_str(), &statbuf)) {
result.error = errno;
} else {
result.mod_time = statbuf.st_mtime;
if (waccess(path.c_str(), this->mode)) {
result.error = errno;
} else {
result.accessible = true;
}
}
// Note that we record the last checked time after the call, on the assumption that in a slow filesystem, the lag comes before the kernel check, not after.
result.stale = false;
result.last_checked = time(NULL);
return result;
return ::access_file(path, this->mode);
}
bool access_tracker_t::access_file_only_cached(const wcstring &path, file_access_attempt_t &attempt) {
@ -162,3 +166,99 @@ file_access_attempt_t access_tracker_t::access_file(const wcstring &path) {
}
return result;
}
lru_cache_impl_t::lru_cache_impl_t() : node_count(0), mouth(L"") {
/* Hook up the mouth to itself: a one node circularly linked list */
mouth.prev = mouth.next = &mouth;
}
void lru_cache_impl_t::evict_node(lru_node_t *condemned_node) {
/* We should never evict the mouth */
assert(condemned_node != NULL && condemned_node != &mouth);
/* Remove it from the linked list */
condemned_node->prev->next = condemned_node->next;
condemned_node->next->prev = condemned_node->prev;
/* Remove us from the set */
node_set.erase(condemned_node);
node_count--;
/* Tell it */
condemned_node->evicted();
}
void lru_cache_impl_t::evict_last_node(void) {
/* Simple */
evict_node(mouth.prev);
}
bool lru_cache_impl_t::evict_node(const wcstring &key) {
/* Construct a fake node as our key */
lru_node_t node_key(key);
/* Look for it in the set */
node_set_t::iterator iter = node_set.find(&node_key);
if (iter == node_set.end())
return false;
/* Evict the given node */
evict_node(*iter);
return true;
}
void lru_cache_impl_t::promote_node(lru_node_t *node) {
/* We should never promote the mouth */
assert(node != &mouth);
/* First unhook us */
node->prev->next = node->next;
node->next->prev = node->prev;
/* Put us after the mouth */
node->next = mouth.next;
node->prev = &mouth;
mouth.next = node;
}
bool lru_cache_impl_t::add_node(lru_node_t *node) {
assert(node != NULL && node != &mouth);
/* Try inserting; return false if it was already in the set */
if (! node_set.insert(node).second)
return false;
/* Update the count */
node_count++;
/* Add the node after the mouth */
node->next = mouth.next;
node->prev = &mouth;
mouth.next = node;
/* Success */
return true;
}
lru_node_t *lru_cache_impl_t::get_node(const wcstring &key) {
lru_node_t *result = NULL;
/* Construct a fake node as our key */
lru_node_t node_key(key);
/* Look for it in the set */
node_set_t::iterator iter = node_set.find(&node_key);
/* If we found a node, promote and return it */
if (iter != node_set.end()) {
result = *iter;
promote_node(result);
}
return result;
}
void lru_cache_impl_t::evict_all_nodes() {
while (node_count > 0) {
evict_last_node();
}
}

69
autoload.h
View file

@ -3,8 +3,8 @@
The classes responsible for autoloading functions and completions.
*/
#ifndef FISH_PARSE_UTIL_H
#define FISH_PARSE_UTIL_H
#ifndef FISH_AUTOLOAD_H
#define FISH_AUTOLOAD_H
#include <wchar.h>
#include <map>
@ -14,9 +14,8 @@
extern const time_t kFishDefaultStalenessInterval;
/** A class responsible for recording an attempt to access a file. */
class file_access_attempt_t {
public:
/** A struct responsible for recording an attempt to access a file. */
struct file_access_attempt_t {
time_t mod_time; /** The modification time of the file */
time_t last_checked; /** When we last checked the file */
bool accessible; /** Whether we believe we could access this file */
@ -32,6 +31,7 @@ struct dereference_less_t {
bool operator()(ptr_t p1, ptr_t p2) const { return *p1 < *p2; }
};
file_access_attempt_t access_file(const wcstring &path, int mode);
/** A class responsible for tracking accesses to files, including auto-expiration. */
class access_tracker_t {
@ -72,4 +72,63 @@ class access_tracker_t {
bool access_file_only_cached(const wcstring &path, file_access_attempt_t &attempt);
};
class lru_node_t {
friend class lru_cache_impl_t;
/** Our linked list pointer */
lru_node_t *prev, *next;
public:
/** The key used to look up in the cache */
const wcstring key;
/** Constructor */
lru_node_t(const wcstring &keyVar) : prev(NULL), next(NULL), key(keyVar) { }
bool operator<(const lru_node_t &other) const { return key < other.key; }
/** Callback when the node is evicted from an LRU cache */
virtual void evicted(void) { }
};
class lru_cache_impl_t {
private:
void promote_node(lru_node_t *);
void evict_node(lru_node_t *node);
void evict_last_node(void);
/** Count of nodes */
unsigned int node_count;
/** The set of nodes */
typedef std::set<lru_node_t *, dereference_less_t> node_set_t;
node_set_t node_set;
/** Head of the linked list */
lru_node_t mouth;
public:
/** Constructor */
lru_cache_impl_t();
/** Returns the node for a given key, or NULL */
lru_node_t *get_node(const wcstring &key);
/** Evicts the node for a given key, returning true if a node was evicted. */
bool evict_node(const wcstring &key);
/** Adds a node under the given key. Returns true if the node was added, false if the node was not because a node with that key is already in the set. */
bool add_node(lru_node_t *node);
/** Evicts all nodes */
void evict_all_nodes(void);
};
/** Template cover to avoid casting */
template<class node_type_t>
class lru_cache_t : public lru_cache_impl_t {
public:
node_type_t *get_node(const wcstring &key) { return static_cast<node_type_t>(lru_cache_impl_t::get_node(key)); }
bool add_node(node_type_t *node) { return lru_cache_impl_t::add_node(node); }
};
#endif

110
parse_util.cpp
View file

@ -54,43 +54,6 @@
#define AUTOLOAD_MIN_AGE 60
/* Get the name of the function that was least recently loaded, if it was loaded before cutoff_access. Return NULL if no function qualifies. */
const wcstring *autoload_t::get_lru_function_name(const wcstring &skip, time_t cutoff_access) const
{
const wcstring *resultName = NULL;
const autoload_function_t *resultFunction = NULL;
autoload_functions_map_t::const_iterator iter;
for (iter = autoload_functions.begin(); iter != autoload_functions.end(); iter++)
{
/* Skip the skip */
if (iter->first == skip) continue;
/* Skip items that are still loading */
if (is_loading(iter->first)) continue;
/* Skip placeholder items */
if (iter->second.is_placeholder) continue;
/* Check cutoff_access */
if (iter->second.load_time > cutoff_access) continue;
/* Remember this if it was used earlier */
if (resultFunction == NULL || iter->second.load_time < resultFunction->load_time) {
resultName = &iter->first;
resultFunction = &iter->second;
}
}
return resultName;
}
void autoload_t::apply_handler_to_nonplaceholder_function_names(void (*handler)(const wchar_t *cmd)) const
{
autoload_functions_map_t::const_iterator iter;
for (iter = autoload_functions.begin(); iter != autoload_functions.end(); iter++)
handler(iter->first.c_str());
}
int parse_util_lineno( const wchar_t *str, int len )
{
/**
@ -638,6 +601,13 @@ void parse_util_token_extent( const wchar_t *buff,
}
autoload_function_t::~autoload_function_t() { }
void autoload_function_t::evicted(void) {
delete this;
}
autoload_t::autoload_t(const wcstring &env_var_name_var, const builtin_script_t * const scripts, size_t script_count) :
env_var_name(env_var_name_var),
builtin_scripts(scripts),
@ -647,50 +617,14 @@ autoload_t::autoload_t(const wcstring &env_var_name_var, const builtin_script_t
void autoload_t::reset( void (*on_load)(const wchar_t *cmd) )
{
if (! autoload_functions.empty()) {
if (on_load) {
/* Call the on_load handler on each real function name. */
this->apply_handler_to_nonplaceholder_function_names(on_load);
}
/* Empty the functino set */
this->remove_all_functions();
}
function_cache.evict_all_nodes();
/* TODO: Must call on_load on all non-placeholders */
}
int autoload_t::unload( const wchar_t *cmd, void (*on_load)(const wchar_t *cmd) )
{
int result = 0;
CHECK( cmd, 0 );
if (this->remove_function_with_name(cmd))
{
if (on_load)
on_load(cmd);
result = 1;
}
return result;
}
/**
Unload one autoloaded item that has expired, that where loaded in
the specified path.
\param skip unloading the the specified file
\param on_load the callback function to call for every unloaded file
*/
void autoload_t::autounload( const wchar_t *skip,
void (*on_load)(const wchar_t *cmd) )
{
if( this->function_count() >= AUTOLOAD_MAX )
{
time_t cutoff_access = time(0) - AUTOLOAD_MIN_AGE;
const wcstring *lru = this->get_lru_function_name(skip, cutoff_access);
if (lru)
unload( lru->c_str(), on_load );
}
return function_cache.evict_node(cmd);
}
int autoload_t::load( const wcstring &cmd,
@ -702,7 +636,6 @@ int autoload_t::load( const wcstring &cmd,
CHECK_BLOCK( 0 );
autounload( cmd.c_str(), on_load );
const env_var_t path_var = env_get_string( env_var_name.c_str() );
/*
@ -791,7 +724,7 @@ int autoload_t::load_internal( const wcstring &cmd,
return 0;
/* Nothing to do if we just checked it */
if (func && time(NULL) - func->load_time <= 1)
if (func && time(NULL) - func->access.last_checked <= 1)
return 0;
/* The source of the script will end up here */
@ -825,24 +758,19 @@ int autoload_t::load_internal( const wcstring &cmd,
*/
for( i=0; i<path_list.size(); i++ )
{
struct stat buf;
wcstring next = path_list.at(i);
wcstring path = next + L"/" + cmd + L".fish";
if( (wstat( path.c_str(), &buf )== 0) &&
(waccess( path.c_str(), R_OK ) == 0) )
{
if( !func || (func->modification_time != buf.st_mtime ) )
{
const file_access_attempt_t access = access_file(path, R_OK);
if (access.accessible) {
if (! func || access.mod_time != func->access.mod_time) {
wcstring esc = escape_string(path, 1);
script_source = L". " + esc;
has_script_source = true;
if( !func )
func = this->create_function_with_name(cmd);
func->modification_time = buf.st_mtime;
func->load_time = time(NULL);
func = new autoload_function_t(cmd);
func->access = access;
if( on_load )
on_load(cmd.c_str());
@ -855,7 +783,7 @@ int autoload_t::load_internal( const wcstring &cmd,
If we are rechecking an autoload file, and it hasn't
changed, update the 'last check' timestamp.
*/
func->load_time = time(NULL);
func->access = access;
}
break;
@ -869,8 +797,8 @@ int autoload_t::load_internal( const wcstring &cmd,
*/
if( !func )
{
func = this->create_function_with_name(cmd);
func->load_time = time(NULL);
func = new autoload_function_t(cmd);
func->access.last_checked = time(NULL);
func->is_placeholder = true;
}
}

38
parse_util.h
View file

@ -7,20 +7,22 @@
#ifndef FISH_PARSE_UTIL_H
#define FISH_PARSE_UTIL_H
#include "autoload.h"
#include <wchar.h>
#include <map>
#include <set>
struct autoload_function_t
struct autoload_function_t : public lru_node_t
{
bool is_placeholder; //whether we are a placeholder that stands in for "no such function"
time_t modification_time; // st_mtime
time_t load_time; // when function was loaded
autoload_function_t(const wcstring &key) : lru_node_t(key), is_placeholder(false) { bzero(&access, sizeof access); }
virtual ~autoload_function_t();
virtual void evicted(void);
autoload_function_t() : is_placeholder(false), modification_time(0), load_time(0) { }
file_access_attempt_t access; /** The last access attempt */
bool is_placeholder; /** Whether we are a placeholder that stands in for "no such function" */
};
struct builtin_script_t;
/**
@ -28,6 +30,9 @@ struct builtin_script_t;
*/
class autoload_t {
private:
/** Access tracker */
lru_cache_t<autoload_function_t> function_cache;
/** The environment variable name */
const wcstring env_var_name;
@ -54,10 +59,6 @@ private:
return is_loading_set.find(name) != is_loading_set.end();
}
autoload_function_t *create_function_with_name(const wcstring &name) {
return &autoload_functions[name];
}
bool remove_function_with_name(const wcstring &name) {
return autoload_functions.erase(name) > 0;
}
@ -79,25 +80,8 @@ private:
return autoload_functions.size();
}
/** Returns the name of the function that was least recently loaded, if it was loaded before cutoff_access. Return NULL if no function qualifies. */
const wcstring *get_lru_function_name(const wcstring &skip, time_t cutoff_access) const;
int load_internal( const wcstring &cmd, void (*on_load)(const wchar_t *cmd), int reload, const wcstring_list_t &path_list );
/**
Unload all autoloaded items that have expired, that where loaded in
the specified path.
\param skip unloading the the specified file
\param on_load the callback function to call for every unloaded file
*/
void autounload( const wchar_t *skip,
void (*on_load)(const wchar_t *cmd) );
void apply_handler_to_nonplaceholder_function_names(void (*handler)(const wchar_t *cmd)) const;
public:
/** Create an autoload_t for the given environment variable name */