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refactor: started refactoring trie api (contains segfaults)

generic-data-trie
Jef Roosens 2022-12-07 12:29:37 +01:00
parent 088322c18f
commit 50ebf86589
Signed by: Jef Roosens
GPG Key ID: B75D4F293C7052DB
4 changed files with 109 additions and 115 deletions
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4
CMakeLists.txt
View File

@ -4,7 +4,7 @@ project(lander C CXX)
set(CMAKE_C_STANDARD 17)
set(CMAKE_CXX_STANDARD 17)
include_directories(crow/include trie/include)
include_directories(trie/include)
add_subdirectory(crow)
add_subdirectory(trie)
@ -16,5 +16,5 @@ else()
endif()
add_executable(lander src/main.cpp)
target_link_libraries(lander PUBLIC trie)
target_link_libraries(lander PUBLIC Crow::Crow trie)
endif()

62
src/main.cpp
View File

@ -7,6 +7,7 @@ extern "C" {
#include "trie.h"
}
static const std::string file_path = "lander.data";
static const std::string index_page = R"(
<!DOCTYPE html>
<html>
@ -38,17 +39,18 @@ crow::response add_redirect(std::string base_url, Trie *trie, const char *url,
// The key already gets copied into the trie, so this pointer is safe to use
// ever after unlocking the trie
trie_wlock(trie);
char *key = trie_add_random(trie, new_entry, secure);
char *key;
TrieExitCode res = trie_add_random(trie, &key, new_entry, secure);
trie_unlock(trie);
if (key == NULL) {
if (res != Ok) {
return crow::response(crow::status::INTERNAL_SERVER_ERROR);
}
std::string res = base_url + key;
std::string out = base_url + key;
free(key);
return crow::response(res);
return crow::response(out);
}
bool store_paste(const char *key, const char *body) {
@ -71,10 +73,11 @@ crow::response add_paste(std::string base_url, Trie *trie, const char *body,
Entry *new_entry = entry_new(Paste, "");
trie_wlock(trie);
char *key = trie_add_random(trie, new_entry, secure);
char *key;
TrieExitCode res = trie_add_random(trie, &key, new_entry, secure);
trie_unlock(trie);
if (key == NULL) {
if (res != Ok) {
return crow::response(crow::status::INTERNAL_SERVER_ERROR);
}
@ -82,10 +85,10 @@ crow::response add_paste(std::string base_url, Trie *trie, const char *body,
return crow::response(crow::status::INTERNAL_SERVER_ERROR);
}
std::string res = base_url + key;
std::string out = base_url + key;
free(key);
return crow::response(res);
return crow::response(out);
}
int main() {
@ -95,26 +98,21 @@ int main() {
ENV(api_key, "LANDER_API_KEY");
ENV(base_url, "LANDER_BASE_URL");
// Initialize trie and populate from data file
Trie *trie = trie_init();
std::string file_path = "lander.data";
std::cout << "Populating trie from file '" << file_path << "'..."
std::cout << "Initializing trie from file '" << file_path << "'..."
<< std::endl;
// Web server hasn't started yet, so there's no point in locking the trie
int count = trie_populate(trie, file_path.c_str());
// Initialize trie and populate from data file
Trie *trie;
int res = trie_init(&trie, file_path.c_str());
if (count == -1) {
std::cout << "An error occured while populating the trie." << std::endl;
if (res != 0) {
std::cout << "An error occured while initializing the trie." << std::endl;
exit(1);
} else {
std::cout << "Added " << count << " (" << trie_size(trie)
<< ") entries to trie." << std::endl;
}
std::cout << "Added " << trie_size(trie) << " entries to trie." << std::endl;
// Create pastes directory if not present
// TODO don't just ignore errors here
mkdir("pastes", 0700);
@ -130,9 +128,10 @@ int main() {
.methods(crow::HTTPMethod::Get)(
[trie](crow::response &res, std::string key) {
trie_rlock(trie);
Entry *entry = trie_search(trie, key.c_str());
Entry *entry;
TrieExitCode status = trie_search(trie, &entry, key.c_str());
if (entry != NULL) {
if (status == Ok) {
if (entry->type == Redirect) {
res.redirect(entry->string);
} else if (entry->type == Paste) {
@ -173,14 +172,17 @@ int main() {
Entry *new_entry = entry_new(Redirect, req.body.c_str());
trie_wlock(trie);
bool added = trie_add(trie, key.c_str(), new_entry);
TrieExitCode status = trie_add(trie, key.c_str(), new_entry);
trie_unlock(trie);
if (!added) {
return crow::response(crow::status::CONFLICT);
}
switch (status) {
case Ok:
return crow::response(base_url + key);
case AlreadyPresent:
return crow::response(crow::status::CONFLICT);
default:
return crow::response(crow::status::INTERNAL_SERVER_ERROR);
}
});
// Add a new Paste with a short randomly generated key
@ -209,10 +211,10 @@ int main() {
Entry *new_entry = entry_new(Paste, "");
trie_wlock(trie);
bool added = trie_add(trie, key.c_str(), new_entry);
TrieExitCode status = trie_add(trie, key.c_str(), new_entry);
trie_unlock(trie);
if (!added) {
if (status != Ok) {
return crow::response(crow::status::CONFLICT);
}

38
trie/include/trie.h
View File

@ -41,23 +41,22 @@ typedef struct entry {
char *string;
} Entry;
typedef enum trie_exit_code {
Ok = 0,
NotFound,
AlreadyPresent,
FileError
} TrieExitCode;
Entry *entry_new(EntryType type, const char *string);
/**
* Allocate and initialize an empty Trie.
* Allocate & initialize a new trie, and populate it with the data from the
* given data file.
*
* @return a pointer to an empty Trie struct
* @return 0 if everything was successful, non-zero otherwise
*/
Trie *trie_init();
/**
* Populate trie with entries stored in the given file.
*
* @param trie
* @param file_path path to file containing entries
* @return amount of entries added; -1 if an error occured
*/
int trie_populate(Trie *trie, const char *file_path);
TrieExitCode trie_init(Trie **trie_ptr, const char *file_path);
/**
* De-allocate a trie by freeing the memory occupied by this trie.
@ -70,10 +69,11 @@ void trie_free(Trie *trie);
* Search for an entry in the trie.
*
* @param trie
* @param entry_ptr pointer to Entry will be stored here, if found
* @param key key representing the entry
* @return pointer to entry; NULL if not found
* @return 0 if the search was successful, 1 if not found
*/
Entry *trie_search(Trie *trie, const char *key);
TrieExitCode trie_search(Trie *trie, Entry **entry_ptr, const char *key);
/**
* Add a string to this trie.
@ -81,12 +81,9 @@ Entry *trie_search(Trie *trie, const char *key);
* @param trie
* @param key key to represent entry with
* @param entry entry to add
* @return true if the trie was changed by this operation, false if it was
* already present
* @return 0 if added, 1 if already in trie, something else if other errors
*/
bool trie_add(Trie *trie, const char *key, Entry *entry);
bool trie_add_no_lock(Trie *trie, const char *key, Entry *entry);
TrieExitCode trie_add(Trie *trie, const char *key, Entry *entry);
/**
* Add an entry by generating a random string as the key.
@ -97,7 +94,8 @@ bool trie_add_no_lock(Trie *trie, const char *key, Entry *entry);
* @return pointer to the generated key. This pointer is safe to use after
* unlocking the trie, and should be freed manually.
*/
char *trie_add_random(Trie *trie, Entry *entry, bool secure);
TrieExitCode trie_add_random(Trie *trie, char **key_ptr, Entry *entry,
bool secure);
/**
* Remove an entry from this trie given its key.

90
trie/src/trie.c
View File

@ -15,39 +15,25 @@ typedef struct ttrie {
pthread_rwlock_t lock;
} Trie;
TrieExitCode trie_add_no_lock(Trie *trie, const char *key, Entry *entry);
/**
* Allocate and initialize an empty Trie
*
* @return pointer to the empty Trie
*/
Trie *trie_init() {
TrieExitCode trie_init(Trie **trie_ptr, const char *file_path) {
// Allocate & initialize trie
Trie *trie = calloc(1, sizeof(Trie));
trie->root = tnode_init();
trie->file_path = strdup(file_path);
pthread_rwlock_init(&trie->lock, NULL);
return trie;
}
/**
* De-allocate a TernaryTree by freeing its entire underlying structure.
*
* @param trie trie to free
*/
void trie_free(Trie *trie) {
tnode_free(trie->root);
free(trie);
}
bool trie_add_no_lock(Trie *trie, const char *key, Entry *entry);
int trie_populate(Trie *trie, const char *file_path) {
trie->file_path = strdup(file_path);
// Populate trie with data from file
FILE *fp = fopen(file_path, "r");
// TODO properly handle this
if (fp == NULL) {
return -1;
return FileError;
}
// We read in lines of at most 8192 characters (sounds like enough)
@ -89,7 +75,19 @@ int trie_populate(Trie *trie, const char *file_path) {
fclose(fp);
return entries;
*trie_ptr = trie;
return Ok;
}
/**
* De-allocate a TernaryTree by freeing its entire underlying structure.
*
* @param trie trie to free
*/
void trie_free(Trie *trie) {
tnode_free(trie->root);
free(trie);
}
typedef struct searchresult {
@ -145,16 +143,16 @@ SearchResult trie_search_node(Trie *trie, const char *key) {
* @param string string to look up
* @return true if the string is present in the trie, false otherwise
*/
Entry *trie_search(Trie *trie, const char *key) {
TrieExitCode trie_search(Trie *trie, Entry **entry_ptr, const char *key) {
SearchResult res = trie_search_node(trie, key);
Entry *return_value = NULL;
if (res.child != NULL) {
return_value = res.child->entry;
if (res.child == NULL) {
return NotFound;
}
return return_value;
*entry_ptr = res.child->entry;
return Ok;
}
/**
@ -165,7 +163,7 @@ Entry *trie_search(Trie *trie, const char *key) {
* @return true if the string wasn't present in the trie and thus added, false
* otherwise
*/
bool trie_add_no_lock(Trie *trie, const char *string, Entry *entry) {
TrieExitCode trie_add_no_lock(Trie *trie, const char *string, Entry *entry) {
size_t i = 0;
uint8_t offset;
TrieNode **node_ptr = &(trie->root);
@ -207,7 +205,7 @@ bool trie_add_no_lock(Trie *trie, const char *string, Entry *entry) {
child_node->entry = entry;
trie->size++;
return true;
return Ok;
}
while (offset < (*child_node_ptr)->string_len) {
@ -258,27 +256,26 @@ bool trie_add_no_lock(Trie *trie, const char *string, Entry *entry) {
} while (string[i] != DELIMITER);
if ((*child_node_ptr)->represents) {
return false;
return AlreadyPresent;
}
(*child_node_ptr)->represents = true;
trie->size++;
return true;
return Ok;
}
bool trie_add(Trie *trie, const char *key, Entry *entry) {
if (trie->file_path != NULL) {
TrieExitCode trie_add(Trie *trie, const char *key, Entry *entry) {
// Easiest way to make sure we don't add duplicate entries
// We use an internal function that doesn't require a read lock, as we're
// already inside a write lock
if (trie_search_node(trie, key).child != NULL) {
return false;
return AlreadyPresent;
}
FILE *fp = fopen(trie->file_path, "a");
if (fp == NULL) {
return false;
return FileError;
}
fputs(key, fp);
@ -287,14 +284,16 @@ bool trie_add(Trie *trie, const char *key, Entry *entry) {
fputs(" ", fp);
fputs(entry->string, fp);
fputs("\n", fp);
}
// This function *should* always return true. Otherwise, the function would've
fclose(fp);
// This function *should* always return Ok. Otherwise, the function would've
// exited because the string was found in the trie.
return trie_add_no_lock(trie, key, entry);
}
char *trie_add_random(Trie *trie, Entry *entry, bool secure) {
TrieExitCode trie_add_random(Trie *trie, char **key_ptr, Entry *entry,
bool secure) {
// Generate random key
bool ok = false;
int key_length = secure ? RANDOM_KEY_LENGTH_LONG : RANDOM_KEY_LENGTH_SHORT;
@ -312,13 +311,11 @@ char *trie_add_random(Trie *trie, Entry *entry, bool secure) {
ok = trie_search_node(trie, key).child == NULL;
}
bool res = trie_add(trie, key, entry);
char *return_value;
TrieExitCode return_value = trie_add(trie, key, entry);
if (res) {
return_value = key;
if (return_value == Ok) {
*key_ptr = key;
} else {
return_value = NULL;
free(key);
}
@ -398,7 +395,4 @@ int trie_rlock(Trie *trie) { return pthread_rwlock_rdlock(&trie->lock); }
int trie_wlock(Trie *trie) { return pthread_rwlock_wrlock(&trie->lock); }
int trie_unlock(Trie *trie) {
printf("sup\n");
return pthread_rwlock_unlock(&trie->lock);
}
int trie_unlock(Trie *trie) { return pthread_rwlock_unlock(&trie->lock); }