BOINC applications may generate graphics, allowing them to provide a screensaver. This API is described here.
BOINC applications may consist of several programs that are executed in sequence; these are called compound applications. This API is described here.
Applications should initialize diagnostics before any other BOINC calls.
Initialization for graphical and compound applications are described elsewhere (see links above). Other applications must call
int boinc_init();
before calling other BOINC functions or doing I/O.
When the application has completed it must call
int boinc_finish(int status);
status is nonzero if an error was encountered.
This call does not return.
int boinc_resolve_filename(char *logical_name, char *physical_name, int len);
or
", html_text("
int boinc_resolve_filename_s(char *logical_name, std::string& physical_name);
"), "
to convert logical file names to physical names.
For example, instead of
f = fopen(\"my_file\", \"r\");
the application might use
", html_text("
string resolved_name;
retval = boinc_resolve_filename(\"my_file\", resolved_name);
if (retval) fail(\"can't resolve filename\");
f = fopen(resolved_name.c_str(), \"r\");
"), "
boinc_resolve_filename() doesn't need to be used for temporary files.
Applications should replace fopen() calls with
boinc_fopen(char* path, char* mode);This deals with platform-specific problems. On Windows, where security and indexing programs can briefly lock files, boinc_fopen() does several retries at 1-second intervals. On Unix, where signals can cause fopen() to fail with EINTR, boinc_fopen checks for this and does a few retries.
Frequency of checkpointing is a user preference (e.g. laptop users might want to checkpoint infrequently). An application must call
int boinc_time_to_checkpoint();
whenever it reaches a point where it is able to checkpoint.
If this returns nonzero,
the application must checkpoint immediately
(i.e., write the state file and flush all output files),
then call
void boinc_checkpoint_completed();
boinc_time_to_checkpoint() is fast,
so it can be called frequently (hundreds or thousands of times a second).
void boinc_begin_critical_section(); void boinc_end_critical_section();Call these around code segments during which you don't want to be suspended or killed by the core client. NOTE: this is done automatically while checkpointing.
To facilitate atomic checkpoint, an application can write to output and
state files using the MFILE class.
class MFILE {
public:
int open(char* path, char* mode);
int _putchar(char);
int puts(char*);
int printf(char* format, ...);
size_t write(const void* buf, size_t size, size_t nitems);
int close();
int flush();
};
MFILE buffers data in memory
and writes to disk only on flush() or close().
This lets you write output files and state files more or less atomically.
By default, the claimed credit of a result is based on the product of its total CPU time and the benchmark values obtained by the core client. This can produce results that are too low if the application uses processor-specific optimizations not present in the core client, is compiled with different compiler settings, or uses a GPU or other non-CPU computing resource. To handle such cases, the following functions can be used.
void boinc_ops_per_cpu_second(double floating_point_ops, double integer_ops);This reports the results of an application-specific benchmark, expressed as number of floating-point and integer operations per CPU second.
void boinc_ops_cumulative(double floating_point_ops, double integer_ops);This reports the total number of floating-point and integer operations since the start of the result. It must be called just before boinc_finish(), and optionally at intermediate points.
The core client GUI displays the percent done of workunits in progress. To keep this display current, an application should periodically call
boinc_fraction_done(double fraction_done);The
fraction_done argument is a rough estimate of the
workunit fraction complete (0 to 1).
This function is fast and can be called frequently.
The following functions get information from the core client; this information may be useful for graphics. ", html_text(" int boinc_get_init_data(APP_INIT_DATA&); struct APP_INIT_DATA { int core_version; char app_name[256]; char project_preferences[65536]; char user_name[256]; char team_name[256]; char project_dir[256]; char boinc_dir[256]; char wu_name[256]; char authenticator[256]; int slot; double user_total_credit; double user_expavg_credit; double team_total_credit; double team_expavg_credit; HOST_INFO host_info; }; "), " to get the following information: "; list_start(); list_item("core version", "The version number of the core client"); list_item("app_name", "The application name (from the server's DB)"); list_item("project_preferences", "An XML string containing the user's project-specific preferences."); list_item("user_name", " the user's 'screen name' on this project."); list_item("team_name", " the user's team name, if any."); list_item("project_dir", "absolute path of project directory"); list_item("boinc_dir", "absolute path of BOINC root directory"); list_item("wu_name", "name of workunit being processed"); list_item("authenticator", "user's authenticator for this project"); list_item("slot", "The number of the app's 'slot' (0, 1, ...)"); list_item("user_total_credit", " user's total work for this project."); list_item("user_expavg_credit", " user's recent average work per day."); list_item("team_total_credit", " team's total work for this project."); list_item("team_expavg_credit", " team's recent average work per day."); list_item("host_info", "A structure describing the host hardware and OS"); list_end(); echo "
An application may call ", html_text(" int boinc_wu_cpu_time(double &cpu_time); "), "to get its total CPU time (from the beginning of the work unit, not just since the last restart). This excludes CPU time used to render graphics.
Some applications may have periods when they don't use much CPU time (e.g. because they're doing network communication). Call the following functions at the start and end of these periods. ",html_text(" void boinc_not_using_cpu(); void boinc_using_cpu(); "), " This allows the BOINC client to schedule other applications during these periods.
If it appears that there is no physical network connection (e.g. gethostbyname() fails for a valid name) then
boinc_need_network().
This will alert the user that a network connection is needed.
boinc_network_poll()
until it returns zero.
boinc_network_done().
This enables that hangup of a modem connection, if needed.
boinc_not_using_cpu() ... boinc_using_cpu().
";
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