feat(lsm): introduce entry handles for concurrent access
parent
0e4e18da6c
commit
f44c512099
GPG Key ID:
B75D4F293C7052DB
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@ -21,27 +21,10 @@ typedef enum lsm_attr_type : uint64_t {
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} lsm_attr_type;
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/**
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* An entry inside an LSM store.
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*
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* Each entry consists of the key it's stored behind, zero or more attributes
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* (metadata) and a data field. The data field can be stored on disk or
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* in-memory, depending on the size.
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* A handle referencing an entry inside a store. Read/write operations from/to
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* the entry go through this handle.
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*/
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typedef struct lsm_entry lsm_entry;
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/**
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* Allocate and initialize a new lsm_entry object.
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*
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* @param ptr where to store newly allocated pointer
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*/
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lsm_error lsm_entry_init(lsm_entry **ptr);
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/**
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* Deallocate an existing lsm_entry object.
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*
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* @param entry object to deallocate
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*/
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void lsm_entry_free(lsm_entry *entry);
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typedef struct lsm_entry_handle lsm_entry_handle;
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/**
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* Checks whether the entry has an attribute with the specified type.
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@ -49,7 +32,7 @@ void lsm_entry_free(lsm_entry *entry);
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* @param entry entry to check
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* @param type type of attribute to check for
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*/
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bool lsm_entry_attr_present(lsm_entry *entry, lsm_attr_type type);
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bool lsm_entry_attr_present(lsm_entry_handle *handle, lsm_attr_type type);
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/**
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* Retrieve the contents of an attribute from an entry, if present
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@ -58,7 +41,7 @@ bool lsm_entry_attr_present(lsm_entry *entry, lsm_attr_type type);
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* @param entry entry to search for
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* @param type type of attribute to return
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*/
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lsm_error lsm_entry_attr_get(lsm_str **out, lsm_entry *entry,
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lsm_error lsm_entry_attr_get(lsm_str **out, lsm_entry_handle *handle,
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lsm_attr_type type);
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/**
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@ -68,7 +51,7 @@ lsm_error lsm_entry_attr_get(lsm_str **out, lsm_entry *entry,
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* @param type type of attribute to add
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* @param data data of attribute; ownership of pointer is taken over
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*/
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lsm_error lsm_entry_attr_insert(lsm_entry *entry, lsm_attr_type type,
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lsm_error lsm_entry_attr_insert(lsm_entry_handle *handle, lsm_attr_type type,
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lsm_str *data);
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/**
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@ -79,7 +62,7 @@ lsm_error lsm_entry_attr_insert(lsm_entry *entry, lsm_attr_type type,
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* @param entry entry to remove attribute from
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* @param type type of attribute to remove
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*/
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lsm_error lsm_entry_attr_remove(lsm_str **out, lsm_entry *entry,
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lsm_error lsm_entry_attr_remove(lsm_str **out, lsm_entry_handle *handle,
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lsm_attr_type type);
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/**
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@ -104,7 +87,7 @@ lsm_error lsm_store_init(lsm_store **ptr);
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* @param db_path path to the database file
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* @param data_path path to the data directory
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*/
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lsm_error lsm_store_open(lsm_store **ptr, lsm_str *db_path, lsm_str *data_path);
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lsm_error lsm_store_load(lsm_store **ptr, lsm_str *db_path, lsm_str *data_path);
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/**
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* Dealocate an existing lsm_store object.
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@ -114,43 +97,45 @@ lsm_error lsm_store_open(lsm_store **ptr, lsm_str *db_path, lsm_str *data_path);
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void lsm_store_free(lsm_store *store);
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/**
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* Retrieve an entry from the store, preparing & locking it for the purpose of
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* reading.
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* Open a read handle to the given entry. This entry must be properly closed
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* using `lsm_store_handle_close`.
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*
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* @param out pointer to store entry pointer
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* @param out pointer to store handle pointer
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* @param store store to retrieve entry from
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* @param key key to search
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*/
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lsm_error lsm_store_get_read(lsm_entry **out, lsm_store *store, lsm_str *key);
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lsm_error lsm_store_open_read(lsm_entry_handle **out, lsm_store *store,
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lsm_str *key);
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/**
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* Retrieve an entry from the store for the purposes of writing. This
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* write-locks the entry.
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* Open a write handle to the given entry. This entry must be properly closed
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* using `lsm_store_handle_close`.
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*
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* @param out pointer to store entry pointer
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* @param out pointer to store handle pointer
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* @param store store to retrieve entry from
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* @param key key to search
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*/
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lsm_error lsm_store_get_write(lsm_entry **out, lsm_store *store, lsm_str *key);
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lsm_error lsm_store_open_write(lsm_entry_handle **out, lsm_store *store,
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lsm_str *key);
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/**
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* Unlock a locked entry.
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* Close an open entry handle.
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*
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* @param store store to unlock entry in
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* @param entry entry to unlock
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* @param store store the handle's entry is stored in
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* @param handle handle to close
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*/
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lsm_error lsm_store_unlock(lsm_store *store, lsm_entry *entry);
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void lsm_entry_close(lsm_entry_handle *handle);
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/**
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* Allocate a new entry in the store with the specified key. The entry returned
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* will be write-locked, and should be unlocked after streaming the necessary
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* data.
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* Insert a new entry into the store, returning a write handle to the newly
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* created entry.
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*
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* @param out pointer to store new entry pointer in
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* @param store store to modify
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* @param key key to add; ownership of key pointer is taken over
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*/
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lsm_error lsm_store_insert(lsm_entry **out, lsm_store *store, lsm_str *key);
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lsm_error lsm_store_insert(lsm_entry_handle **out, lsm_store *store,
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lsm_str *key);
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/**
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* Append new data to the given entry, which is expected to be in the store.
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@ -162,7 +147,7 @@ lsm_error lsm_store_insert(lsm_entry **out, lsm_store *store, lsm_str *key);
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* @param entry entry to append data to
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* @param data data to append
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*/
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lsm_error lsm_store_data_write(lsm_store *store, lsm_entry *entry,
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lsm_error lsm_entry_data_append(lsm_store *store, lsm_entry_handle *handle,
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lsm_str *data);
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#endif
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@ -13,7 +13,14 @@ typedef struct lsm_attr {
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lsm_str *str;
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} lsm_attr;
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struct lsm_entry {
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/**
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* An entry inside an LSM store.
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*
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* Each entry consists of the key it's stored behind, zero or more attributes
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* (metadata) and a data field. The data field can be stored on disk or
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* in-memory, depending on the size.
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*/
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typedef struct lsm_entry {
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lsm_str *key;
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struct {
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uint64_t count;
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@ -28,7 +35,21 @@ struct lsm_entry {
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} value;
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bool on_disk;
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} data;
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};
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} lsm_entry;
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/**
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* Allocate and initialize a new lsm_entry object.
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*
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* @param ptr where to store newly allocated pointer
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*/
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lsm_error lsm_entry_init(lsm_entry **ptr);
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/**
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* Deallocate an existing lsm_entry object.
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*
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* @param entry object to deallocate
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*/
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void lsm_entry_free(lsm_entry *entry);
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typedef struct lsm_entry_wrapper {
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pthread_rwlock_t lock;
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@ -36,6 +57,14 @@ typedef struct lsm_entry_wrapper {
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} lsm_entry_wrapper;
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lsm_error lsm_entry_wrapper_init(lsm_entry_wrapper **ptr);
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void lsm_entry_wrapper_free(lsm_entry_wrapper *wrapper);
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struct lsm_entry_handle {
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lsm_entry_wrapper *wrapper;
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FILE *f;
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};
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lsm_error lsm_entry_handle_init(lsm_entry_handle **out);
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struct lsm_store {
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lsm_trie *trie;
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@ -27,7 +27,7 @@ lsm_error lsm_store_init(lsm_store **ptr) {
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return lsm_error_ok;
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}
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lsm_error lsm_store_open(lsm_store **ptr, lsm_str *db_path,
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lsm_error lsm_store_load(lsm_store **ptr, lsm_str *db_path,
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lsm_str *data_path) {
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lsm_store *store;
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LSM_RES(lsm_store_init(&store));
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@ -42,12 +42,13 @@ lsm_error lsm_store_open(lsm_store **ptr, lsm_str *db_path,
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return lsm_error_ok;
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}
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lsm_error lsm_store_get_read(lsm_entry **out, lsm_store *store, lsm_str *key) {
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lsm_error lsm_store_open_read(lsm_entry_handle **out, lsm_store *store,
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lsm_str *key) {
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lsm_entry_wrapper *wrapper;
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LSM_RES(lsm_trie_search((void **)&wrapper, store->trie, key));
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// We don't want to block the thread
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// Try to get a read lock on the entry's lock
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if (pthread_rwlock_tryrdlock(&wrapper->lock) != 0) {
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return lsm_error_lock_busy;
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}
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@ -62,8 +63,17 @@ lsm_error lsm_store_get_read(lsm_entry **out, lsm_store *store, lsm_str *key) {
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return lsm_error_not_found;
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}
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lsm_entry_handle *handle;
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lsm_error res = lsm_entry_handle_init(&handle);
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if (res != lsm_error_ok) {
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pthread_rwlock_unlock(&wrapper->lock);
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return res;
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}
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// Open a new file descriptor if needed
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if (entry->data.on_disk && (entry->data.value.file == NULL)) {
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if (entry->data.on_disk) {
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char path[store->data_path->len + entry->key->len + 2];
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sprintf(path, "%s/%s", lsm_str_ptr(store->data_path),
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lsm_str_ptr(entry->key));
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@ -71,36 +81,111 @@ lsm_error lsm_store_get_read(lsm_entry **out, lsm_store *store, lsm_str *key) {
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FILE *f = fopen(path, "rb");
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if (f == NULL) {
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free(handle);
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return lsm_error_failed_io;
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}
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entry->data.value.file = f;
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handle->f = f;
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}
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handle->wrapper = wrapper;
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*out = handle;
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return lsm_error_ok;
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}
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lsm_error lsm_store_insert(lsm_entry **out, lsm_store *store, lsm_str *key) {
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lsm_error lsm_store_open_write(lsm_entry_handle **out, lsm_store *store,
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lsm_str *key) {
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lsm_entry_wrapper *wrapper;
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LSM_RES(lsm_trie_search((void **)&wrapper, store->trie, key));
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// Try to get a write lock on the entry's lock
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// TODO make this timeout to not block
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if (pthread_rwlock_wrlock(&wrapper->lock) != 0) {
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return lsm_error_lock_busy;
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}
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lsm_entry *entry = wrapper->entry;
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// While the trie's data field will never be NULL, the actual entry pointer
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// might be
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if (entry == NULL) {
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pthread_rwlock_unlock(&wrapper->lock);
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return lsm_error_not_found;
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}
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lsm_entry_handle *handle;
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lsm_error res = lsm_entry_handle_init(&handle);
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if (res != lsm_error_ok) {
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pthread_rwlock_unlock(&wrapper->lock);
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return res;
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}
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// Open a new file descriptor if needed
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if (entry->data.on_disk) {
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char path[store->data_path->len + entry->key->len + 2];
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sprintf(path, "%s/%s", lsm_str_ptr(store->data_path),
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lsm_str_ptr(entry->key));
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FILE *f = fopen(path, "wb");
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if (f == NULL) {
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free(handle);
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return lsm_error_failed_io;
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}
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handle->f = f;
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}
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handle->wrapper = wrapper;
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*out = handle;
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return lsm_error_ok;
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}
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lsm_error lsm_store_insert(lsm_entry_handle **out, lsm_store *store,
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lsm_str *key) {
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// TODO what happens when two inserts to the same key happen at the same time?
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lsm_entry_wrapper *wrapper;
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LSM_RES(lsm_entry_wrapper_init(&wrapper));
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pthread_rwlock_wrlock(&wrapper->lock);
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lsm_error res = lsm_trie_insert(store->trie, key, wrapper);
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// Check if entry isn't already present in advance
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if (res != lsm_error_ok) {
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lsm_entry_wrapper_free(wrapper);
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return res;
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}
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lsm_entry *entry;
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LSM_RES(lsm_entry_init(&entry));
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entry->key = key;
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wrapper->entry = entry;
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pthread_rwlock_wrlock(&wrapper->lock);
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// TODO mem leak if already present
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LSM_RES(lsm_trie_insert(store->trie, key, wrapper));
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lsm_entry_handle *handle;
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LSM_RES(lsm_entry_handle_init(&handle));
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*out = entry;
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// No need to set the handle's file, as the entry doesn't have any data yet
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handle->wrapper = wrapper;
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*out = handle;
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return lsm_error_ok;
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}
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lsm_error lsm_store_data_write(lsm_store *store, lsm_entry *entry,
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lsm_error lsm_entry_data_append(lsm_store *store, lsm_entry_handle *handle,
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lsm_str *data) {
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lsm_entry *entry = handle->wrapper->entry;
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uint64_t new_len = entry->data.len + lsm_str_len(data);
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const char *data_s = lsm_str_ptr(data);
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@ -124,13 +209,13 @@ lsm_error lsm_store_data_write(lsm_store *store, lsm_entry *entry,
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sprintf(path, "%s/%s", lsm_str_ptr(store->data_path),
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lsm_str_ptr(entry->key));
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FILE *f = fopen(path, "w");
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FILE *f = fopen(path, "ab");
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if (f == NULL) {
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return lsm_error_failed_io;
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}
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entry->data.value.file = f;
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handle->f = f;
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entry->data.on_disk = true;
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// TODO free old buff, write original data to file
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@ -141,7 +226,7 @@ lsm_error lsm_store_data_write(lsm_store *store, lsm_entry *entry,
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// TODO what happens when I/O fails?
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while (written < data->len) {
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written += fwrite(&data_s[written], sizeof(char), data->len - written,
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entry->data.value.file);
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handle->f);
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}
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}
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@ -32,16 +32,40 @@ lsm_error lsm_entry_wrapper_init(lsm_entry_wrapper **ptr) {
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return lsm_error_ok;
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}
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bool lsm_entry_attr_present(lsm_entry *entry, lsm_attr_type type) {
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return (entry->attrs.bitmap & type) != 0;
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void lsm_entry_wrapper_free(lsm_entry_wrapper *wrapper) { free(wrapper); }
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lsm_error lsm_entry_handle_init(lsm_entry_handle **out) {
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lsm_entry_handle *handle = calloc(1, sizeof(lsm_entry_handle));
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if (handle == NULL) {
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return lsm_error_failed_alloc;
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}
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lsm_error lsm_entry_attr_get(lsm_str **out, lsm_entry *entry,
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*out = handle;
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return lsm_error_ok;
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}
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void lsm_entry_close(lsm_entry_handle *handle) {
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if (handle->f != NULL) {
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fclose(handle->f);
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}
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pthread_rwlock_unlock(&handle->wrapper->lock);
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free(handle);
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}
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bool lsm_entry_attr_present(lsm_entry_handle *handle, lsm_attr_type type) {
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return (handle->wrapper->entry->attrs.bitmap & type) != 0;
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}
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lsm_error lsm_entry_attr_get(lsm_str **out, lsm_entry_handle *handle,
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lsm_attr_type type) {
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if (!lsm_entry_attr_present(entry, type)) {
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if (!lsm_entry_attr_present(handle, type)) {
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return lsm_error_not_found;
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}
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lsm_entry *entry = handle->wrapper->entry;
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uint64_t i = 0;
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while (entry->attrs.items[i].type != type) {
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@ -53,12 +77,14 @@ lsm_error lsm_entry_attr_get(lsm_str **out, lsm_entry *entry,
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return lsm_error_ok;
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}
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lsm_error lsm_entry_attr_remove(lsm_str **out, lsm_entry *entry,
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lsm_error lsm_entry_attr_remove(lsm_str **out, lsm_entry_handle *handle,
|
||||
lsm_attr_type type) {
|
||||
if (!lsm_entry_attr_present(entry, type)) {
|
||||
if (!lsm_entry_attr_present(handle, type)) {
|
||||
return lsm_error_not_found;
|
||||
}
|
||||
|
||||
lsm_entry *entry = handle->wrapper->entry;
|
||||
|
||||
if (entry->attrs.count == 1) {
|
||||
*out = entry->attrs.items[0].str;
|
||||
|
||||
|
|
@ -99,12 +125,14 @@ lsm_error lsm_entry_attr_remove(lsm_str **out, lsm_entry *entry,
|
|||
return lsm_error_ok;
|
||||
}
|
||||
|
||||
lsm_error lsm_entry_attr_insert(lsm_entry *entry, lsm_attr_type type,
|
||||
lsm_error lsm_entry_attr_insert(lsm_entry_handle *handle, lsm_attr_type type,
|
||||
lsm_str *data) {
|
||||
if (lsm_entry_attr_present(entry, type)) {
|
||||
if (lsm_entry_attr_present(handle, type)) {
|
||||
return lsm_error_already_present;
|
||||
}
|
||||
|
||||
lsm_entry *entry = handle->wrapper->entry;
|
||||
|
||||
lsm_attr *new_attrs =
|
||||
realloc(entry->attrs.items, (entry->attrs.count + 1) * sizeof(lsm_attr));
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue