DB Refactor Design (code committed)
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Link to discussion on Developer Forum: <http://community.pbspro.org/t/design-for-refactoring-pbs-database-code/2009>
Link to issue: <issue link if available>
Link to pull request: <PR link if available>
For easy maintainability, current database-related code within the PBS server needs to be refactored into a separate pluggable dynamic library. And this design page discusses the APIs using which PBS server can talk to Libdb, the database dynamic library using which PBS can talk to the database. Another motivation behind this refactoring is the added advantage of moving to any database without having to do major code changes within PBS itself.
1.1. Files: List of files PBS will need to have database support.
PBS_EXEC/lib/libdb.so
Description: This dynamic library will have the functionality for the PBS server to access the database.
PBS_EXEC/libexec/pbs_db_utility
Description: This script will house all the supporting routines needed by the database. Example routines to install the PBS database, upgrade the database, etc.
Usage: PBS_EXEC/libexec/pbs_db_utility <install_db | upgrade_db>
Parameters:
install_db: Create and initialize the dataservice instance.
upgrade_db: Upgrade the database.
PBS_EXEC/libexec/pbs_db_env
Description: This script will initialize the environment with information related to the database installation path.
PBS_EXEC/include/pbs_db.h
Description: This header file will provide declarations for APIs and argument structures listed below.
conn_db_handle: Pointer used to maintain the database connection information.
void *conn_db_handle; /* opaque database handle */pbs_db_obj_info_t: Wrapper object structure. It contains a pointer to one of the several database structures. Most of the database manipulation/query functions take this structure as a parameter. Depending on the contained structure type, an appropriate internal database manipulation/query function is eventually called. This allows keeping the interface simpler and generic.
struct pbs_db_obj_info {
int pbs_db_obj_type; /* identifies the contained object type */
union {
pbs_db_job_info_t *pbs_db_job; /* map database job structure to C */
pbs_db_jobscr_info_t *pbs_db_jobscr; /* map database job script to C */
pbs_db_resv_info_t *pbs_db_resv; /* map database resv structure to C */
pbs_db_svr_info_t *pbs_db_svr; /* map database server structure to C */
pbs_db_que_info_t *pbs_db_que; /* map database queue structure to C */
pbs_db_node_info_t *pbs_db_node; /* map database node structure to C */
pbs_db_sched_info_t *pbs_db_sched; /* map database scheduler structure to C */
pbs_db_mominfo_time_t *pbs_db_mominfo_tm; /* map database mominfo_time structure to C */
} pbs_db_un;
};
typedef struct pbs_db_obj_info pbs_db_obj_info_t;
/* Structure used to map database job structure to C */
struct pbs_db_job_info {
char ji_jobid[PBS_MAXSVRJOBID + 1]; /* job identifier */
INTEGER ji_state; /* Internal copy of state */
INTEGER ji_substate; /* job sub-state */
INTEGER ji_svrflags; /* server flags */
INTEGER ji_numattr; /* not used */
INTEGER ji_ordering; /* special scheduling ordering */
INTEGER ji_priority; /* priority */
BIGINT ji_stime; /* time job started execution */
BIGINT ji_endtBdry; /* estimate upper bound on end time */
char ji_queue[PBS_MAXQUEUENAME + 1]; /* name of current queue */
char ji_destin[PBS_MAXROUTEDEST + 1]; /* dest from qmove/route */
INTEGER ji_un_type; /* job's queue type */
INTEGER ji_momaddr; /* host addr of Server */
INTEGER ji_momport; /* port # */
INTEGER ji_exitstat; /* job exit status from MOM */
BIGINT ji_quetime; /* time entered queue */
BIGINT ji_rteretry; /* route retry time */
INTEGER ji_fromsock; /* socket job coming over */
BIGINT ji_fromaddr; /* host job coming from */
char ji_4jid[8]; /* extended job save data */
char ji_4ash[8]; /* extended job save data */
INTEGER ji_credtype; /* credential type */
BIGINT ji_qrank; /* sort key for db query */
pbs_db_attr_list_t db_attr_list; /* list of attributes for database */
};
typedef struct pbs_db_job_info pbs_db_job_info_t;
/* Structure used to map database resv structure to C */
struct pbs_db_resv_info {
char ri_resvid[PBS_MAXSVRJOBID + 1]; /* reservation identifier */
char ri_queue[PBS_MAXQUEUENAME + 1]; /* queue used by reservation */
INTEGER ri_state; /* internal copy of state */
INTEGER ri_substate; /* substate of resv state */
BIGINT ri_stime; /* left window boundry */
BIGINT ri_etime; /* right window boundry */
BIGINT ri_duration; /* reservation duration */
INTEGER ri_tactive; /* time reservation became active */
INTEGER ri_svrflags; /* server flags */
INTEGER ri_numattr; /* not used */
INTEGER ri_resvTag; /* not used */
INTEGER ri_un_type; /* not used */
INTEGER ri_fromsock; /* resv from sock */
BIGINT ri_fromaddr; /* resv from sock addr */
pbs_db_attr_list_t db_attr_list; /* list of attributes */
};
typedef struct pbs_db_resv_info pbs_db_resv_info_t;
/* Structure used to map database server structure to C */
struct pbs_db_svr_info {
BIGINT sv_jobidnumber;
pbs_db_attr_list_t db_attr_list; /* list of attributes */
};
typedef struct pbs_db_svr_info pbs_db_svr_info_t;
/* Structure used to map database scheduler structure to C */
struct pbs_db_sched_info {
char sched_name[PBS_MAXSCHEDNAME+1]; /* sched name */
pbs_db_attr_list_t db_attr_list; /* list of attributes */
};
typedef struct pbs_db_sched_info pbs_db_sched_info_t;
/* Structure used to map database queue structure to C */
struct pbs_db_que_info {
char qu_name[PBS_MAXQUEUENAME +1]; /* queue name */
INTEGER qu_type; /* queue type: exec, route */
pbs_db_attr_list_t db_attr_list; /* list of attributes */
};
typedef struct pbs_db_que_info pbs_db_que_info_t;
/* Structure used to map database node structure to C */
struct pbs_db_node_info {
char nd_name[PBS_MAXSERVERNAME+1]; /* vnode's name */
INTEGER nd_index; /* global node index */
BIGINT mom_modtime; /* node config update time */
char nd_hostname[PBS_MAXSERVERNAME+1]; /* node hostname */
INTEGER nd_state; /* state of node */
INTEGER nd_ntype; /* node type */
char nd_pque[PBS_MAXSERVERNAME+1]; /* queue to which it belongs */
pbs_db_attr_list_t db_attr_list; /* list of attributes */
};
typedef struct pbs_db_node_info pbs_db_node_info_t;
/* Structure used to map database mominfo_time structure to C */
struct pbs_db_mominfo_time {
BIGINT mit_time; /* time of the host to vnode map */
INTEGER mit_gen; /* generation of the host to vnode map */
};
typedef struct pbs_db_mominfo_time pbs_db_mominfo_time_t;
/* Structure used to map database job script to C */
struct pbs_db_jobscr_info {
char ji_jobid[PBS_MAXSVRJOBID + 1]; /* job identifier */
TEXT script; /* job script */
};
typedef struct pbs_db_jobscr_info pbs_db_jobscr_info_t;
pbs_db_query_options_t: Structure used to pass database query options to database functions. Flags field can be used to pass any flags to a query function. Timestamp field can be used to pass a timestamp, to return rows that have a modification timestamp newer (more recent) than the timestamp passed. (Basically to return rows that have been modified since a point of time)
The structure used to pass database query options to database functions
struct pbs_db_query_options {
int flags; /* Flags field can be used to pass any flags to a query function. */
time_t timestamp; /* Timestamp field can be used to pass a timestamp, to return rows that have a modification timestamp newer (more recent) than the timestamp passed. (Basically to return rows that have been modified since a point of time) */
};
typedef struct pbs_db_query_options pbs_db_query_options_t;
query_cb_t: Function pointer for call back function to process the data returned by the database. For each row/record returned by the search result, the function pointed by this pointer is called and the result is processed so that PBS can use it.
typedef int (*query_cb_t) (pbs_db_obj_info_t *, int *);
pbs_db_attr_list_t: Structure used to map database attr structure to C.
The structure used to map database attr structure to C
1.2. APIs from libdb.so
1.2.1. PBS Objects: Libdb APIs can work with below mentioned PBS objects.
PBS_DB_JOB: To save and update PBS job objects
PBS_DB_RESV: To save and update PBS reservation objects
PBS_DB_SVR: To save and update PBS server objects
PBS_DB_NODE: To save and update PBS node objects
PBS_DB_QUE: To save and update PBS queue objects
PBS_DB_JOBSCR: To save and update PBS job scripts
PBS_DB_SCHED: To save and update the PBS scheduler objects.
PBS_DB_MOMINFO_TIME: To save/update PBS mominfo_time
1.2.2. pbs_db_connect
Description: Setup a persistent database connection for further use by APIs which will work on PBS objects. On success return the connection information.
Signature:
int pbs_db_connect(void *conn_db_handle, char *pbs_ds_host, int pbs_ds_port, int timeout)
Parameters:
conn_db_handle[out]: This pointer will have connection information for the database on successfull connection.
pbs_data_service_host[in]: Hostname information where the database is running.
pbs_data_service_port[in]: Port number information where the database is running.
timeout[in]: Timeout in seconds before the API will return if it is taking too long to connect.
Returns: Error code
0: On successful connection setup to the database.
!0: On connection failure.
1.2.3. pbs_db_disconnect
Description: Disconnect the PBS server from a database connection.
Signature:
int pbs_db_disconnect(void *conn_db_handle)
Parameters:
conn_db_handle[in]: Connection handler to the database which was created by pbs_db_connect.
Returns: Returns status of the disconnection.
0 - for successful database disconnect.
-1 - for failure
1.2.4. pbs_db_save_obj
Description: PBS can use this API to save any of the PBS Objects listed above to the database. Save operation can be an insert or update.
Signature:
int pbs_db_save_obj(void *conn_db_handle, pbs_db_obj_info_t *obj, int savetype)
Parameters:
conn_db_handle[in]: Connection handler to the database which was created by pbs_db_connect.
obj[in]: The PBS object to save. Based on the type defined within obj structure, right PBS object will be picked and dealt with.
savetype[in]: OBJ_SAVE_QS for quick save and OBJ_SAVE_NEW for insert.
Returns: Error code.
-1 - Execution of prepared statement failed.
0 - Success and > 0 rows were affected.
1 - Execution succeeded but the statement did not affect any rows.
1.2.5. pbs_db_delete_obj
Description: This API lets PBS delete PBS objects PBS_DB_JOB, PBS_DB_RESV, PBS_DB_NODE, PBS_DB_QUE and PBS_DB_SCHED from the database.
Signature:
int pbs_db_delete_obj(void *conn_db_handle, pbs_db_obj_info_t *obj)
Parameters:
conn_db_handle[in]: Connection handler to the database which was created by pbs_db_connect.
obj[in]: PBS object information to be deleted. Based on the type defined within the obj structure, the right PBS object will be picked and dealt with.
Returns: Error code.
-1 - Failure
0 - Success
1 - Success but no rows deleted
1.2.6. pbs_db_load_obj
Description: This API lets PBS load objects data from the database. This API can work with any of the PBS objects.
Signature:
int pbs_db_load_obj(void *conn_db_handle, pbs_db_obj_info_t *obj)
Parameters:
conn_db_handle[in]: Connection handler to the database which was created by pbs_db_connect.
obj[in/out] - PBS object information to be loaded from the database. Based on the type defined within obj structure, right PBS object will be picked and dealt with.
Returns: Error code
-1 - Failure
0 - Success
1 - Success but no rows loaded
1.2.7. pbs_db_search
Description: This API can be used to find/search PBS objects PBS_DB_JOB, PBS_DB_RESV, PBS_DB_NODE, PBS_DB_QUE and PBS_DB_SCHED in the database. This API takes a pointer to the callback function as an argument that will work on the records returned from the database based on the query specified by the PBS.
Signature:
int pbs_db_search(void *conn_db_handle, pbs_db_obj_info_t *obj, pbs_db_query_options_t *opts, query_cb_t query_cb)
Parameters:
conn_db_handle[in]: Connection handler to the database which was created by pbs_db_connect.
obj[in/out]: Information of the object to be found.
opts[in]: Any other custom options (like flags, timestamp) for the query to the database.
query_cb[in]: Function pointer to a callback function that will process the each record returned by the database for the find query made.
Returns: Error code
-1 - Failure
0> - Success
0 - Success but no rows found
1.2.8. pbs_db_del_attr_obj
Description: This API can be used to delete attributes of a PBS object.
Signature:
int pbs_db_delete_attr_obj(void *conn, pbs_db_obj_info_t *obj, void *obj_id, pbs_db_attr_list_t *db_attr_list)
Parameters:
conn_db_handle[in]: Connection handler to the database which was created by pbs_db_connect.
obj[in]: Information of the object to be found.
obj_id[in]: Object id for the delete attributes action.
attr_list[in]: List of attributes to be deleted from DB.
Returns: Error code
0 - Success
Non zero - On Failure
1.2.9. pbs_start_db
Description: This API can be used to start the database instance.
Signature:
int pbs_start_db(char *pbs_ds_host, int pbs_ds_port)
Returns: Status code
0 - Success
Non zero - On Failure
1.2.10. pbs_stop_db
Description: This API can be used to stop the database instance.
Signature:
int pbs_stop_db(char *pbs_ds_host, int pbs_ds_port)
Returns: Status code
0 - Success
Non zero - On Failure
1.2.11. pbs_status_db
Description: This API can be used to check if the database instance is running.
Signature:
int pbs_status_db(char *pbs_ds_host, int pbs_ds_port)
Returns: Status code
1 - Database is not running.
2 - Database is running on a different host.
0 - Database is running on the localhost.
-1 - On Failure
1.2.12. pbs_db_password
Description: This API can be used to change the database user and password for the database instance.
Signature:
int pbs_db_password(void *conn_db_handle, char *user_name, char *password, char *old_user)
Parameters:
conn_db_handle[in]: Connection handler to the database which was created by pbs_db_connect.
user_name[in]: Database user name.
password[in]: New password for the database.
old_user[in]: old database user name used in case of -C option to change database user.
Returns: Error code
0 - Success
Non zero - On Failure
1.2.12. pbs_db_get_errmsg
Description: This API can be used to get the error messages from the database library. When any of the above-listed APIs fail, this API can be used to get the error message from libdb.
Signature:
void pbs_db_get_errmsg(int failcode, char **errmsg)
Parameters:
failcode[in]: Error code returned by one of the above APIs.
errmsg[out]: returns the DB error message if any.