Ubuntu Manpage: notcurses_stats - notcurses runtime statistics

Provided by: libnotcurses-core-dev_3.0.7+dfsg.1-1ubuntu3_amd64

NAME

       notcurses_stats - notcurses runtime statistics

SYNOPSIS

       #include <notcurses/notcurses.h>

              typedef struct ncstats {
                // purely increasing stats
                uint64_t renders;          // successful ncpile_render() runs
                uint64_t writeouts;        // successful ncpile_rasterize() runs
                uint64_t failed_renders;   // aborted renders, should be 0
                uint64_t failed_writeouts; // aborted writes
                uint64_t raster_bytes;     // bytes emitted to ttyfp
                int64_t raster_max_bytes;  // max bytes emitted for a frame
                int64_t raster_min_bytes;  // min bytes emitted for a frame
                uint64_t render_ns;        // nanoseconds spent rendering
                int64_t render_max_ns;     // max ns spent for a frame
                int64_t render_min_ns;     // min ns spent for a frame
                uint64_t raster_ns;        // nanoseconds spent rasterizing
                int64_t raster_max_ns;     // max ns spent in raster for a frame
                int64_t raster_min_ns;     // min ns spent in raster for a frame
                uint64_t writeout_ns;      // ns spent writing frames to terminal
                int64_t writeout_max_ns;   // max ns spent writing out a frame
                int64_t writeout_min_ns;   // min ns spent writing out a frame
                uint64_t cellelisions;     // cells elided entirely
                uint64_t cellemissions;    // cells emitted
                uint64_t fgelisions;       // RGB fg elision count
                uint64_t fgemissions;      // RGB fg emissions
                uint64_t bgelisions;       // RGB bg elision count
                uint64_t bgemissions;      // RGB bg emissions
                uint64_t defaultelisions;  // default color was emitted
                uint64_t defaultemissions; // default color was elided
                uint64_t refreshes;        // refreshes (unoptimized redraws)
                uint64_t sprixelemissions; // sprixel draw count
                uint64_t sprixelelisions;  // sprixel elision count
                uint64_t sprixelbytes;     // sprixel bytes emitted
                uint64_t appsync_updates;  // application-synchronized updates
                uint64_t input_events;     // inputs received or synthesized
                uint64_t input_errors;     // errors processing input
                uint64_t hpa_gratuitous;   // gratuitous HPAs issued
                uint64_t cell_geo_changes; // cell geometry changes (resizes)
                uint64_t pixel_geo_changes;// pixel geometry changes (font resize)

                // current state -- these can decrease
                uint64_t fbbytes;          // bytes devoted to framebuffers
                unsigned planes;           // planes currently in existence
              } ncstats;

       ncstats* notcurses_stats_alloc(struct notcurses* nc);

       void notcurses_stats(struct notcurses* nc, ncstats* stats);

       void notcurses_stats_reset(struct notcurses* nc, ncstats* stats);

DESCRIPTION

notcurses_stats_alloc allocates an ncstats object. This should be used rather than
allocating the object in client code, to future-proof against the struct being enlarged by
later Notcurses versions.

notcurses_stats acquires an atomic snapshot of statistics, primarily related to
notcurses_render(3). notcurses_stats_reset does the same, but also resets all cumulative
stats (immediate stats such as fbbytes are not reset).

renders is the number of successful calls to notcurses_render(3) or
ncpile_render_to_buffer(3). failed_renders is the number of unsuccessful calls to these
functions. failed_renders should be 0; renders are not expected to fail except under
exceptional circumstances. should notcurses_render(3) fail while writing out a frame to
the terminal, it counts as a failed render.

raster_max_bytes and raster_min_bytes track the maximum and minimum number of bytes used
rasterizing a frame. A given state of Notcurses does not correspond to a unique number of
bytes; the size is also dependent on the existing terminal state. As a first
approximation, the time a terminal takes to ingest and reflect a frame is dependent on the
size of the rasterized frame.

render_ns, render_max_ns, and render_min_ns track the total amount of time spent rendering
frames in nanoseconds. Rendering takes place in ncpile_render (called by
notcurses_render(3) and ncpile_render_to_buffer). This step is independent of the
terminal.

raster_ns, raster_max_ns, and raster_min_ns track the total amount of time spent
rasterizing frames in nanoseconds. Rasterizing takes place in ncpile_raster (called by
notcurses_raster(3) and ncpile_render_to_buffer). This step depends on the terminal
definitions. The same frame might not rasterize to the same bytes for different
terminals.

writeout_ns, writeout_max_ns, and writeout_min_ns track the total amount of time spent
writing frames to the terminal. This takes place in ncpile_rasterize (called by
notcurses_render(3)).

cellemissions reflects the number of EGCs written to the terminal. cellelisions reflects
the number of cells which were not written, due to damage detection.

refreshes is the number of times notcurses_refresh has been successfully executed.

fbbytes is the total number of bytes devoted to framebuffers throughout the struct
notcurses context. planes is the number of planes in the context. Neither of these stats
can reach 0, due to the mandatory standard plane.

sprixelemissions is the number of sprixel draws. sprixelelisions is the number of times a
sprixel was elided--essentially, the number of times a sprixel appeared in a rendered
frame without freshly drawing it. sprixelbytes is the number of bytes used for sprixel
drawing. It does not include move/delete operations, nor glyphs used to erase sprixels.

input_errors is the number of errors while processing input, e.g. malformed control
sequences or invalid UTF-8 (see utf8(7)).

hpa_gratuitous is the number of hpa (horizontal position absolute, see terminfo(5))
control sequences issued where not strictly necessary. This is done to cope with
fundamental ambiguities regarding glyph width. It is not generally possible to know how
wide a glyph will be rendered on a given combination of font, font rendering engine, and
terminal. Indeed, it is not even generally possible to know how many glyphs will result
from a sequence of EGCs. As a result, Notcurses sometimes issues "gratuitous" hpa
controls.

cell_geo_changes is the number of changes to the visible area's cell geometry. The cell
geometry changes whenever the visible area is resized without a corresponding cell-pixel
geometry change. pixel_geo_changes is the number of changes to cells' pixel geometry
(i.e. the height and width of each cell), and changes whenever the font size changes.
Both can change at the same time if e.g. a terminal undergoes a font size change without
changing its total size.

NOTES

       Unsuccessful render operations do not contribute to the render timing stats.

       Linux framebuffer bitmaps are  not  written  through  the  terminal  device,  but  instead
       directly  into  the  memory-mapped  framebuffer (see mmap(2)).  Bytes used for framebuffer
       graphics are thus independent of  bytes  written  to  the  terminal.   This  explains  why
       sprixelbytes may be surprising given the value of raster_bytes.

RETURN VALUES

       Neither  notcurses_stats  nor  notcurses_stats_reset can fail.  Neither returns any value.
       notcurses_stats_alloc returns a valid ncstats object on success,  or  NULL  on  allocation
       failure.

AUTHORS