real_tabasco_sauce/0ad
1
0
Fork 0
forked from 0ad/0ad
Code Pull Requests Actions Activity

documented and revised after review by philip (thanks!) - progress is now calculated from estimated duration; next instead of current description is returned

Browse Source 
This was SVN commit r2032.
This commit is contained in:
janwas 2005-03-21 13:33:21 +00:00
parent 046e1e3adc
commit 5e3b0f06ec
2 changed files with 109 additions and 56 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

120
source/ps/Loader.cpp
View File

@ -1,18 +1,27 @@
// FIFO queue of load 'functors' with time limit; enables displaying
// load progress without resorting to threads (complicated).
//
// Jan Wassenberg, initial implementation finished 2005-03-21
// jan@wildfiregames.com
#include "precompiled.h"
#include <deque>
#include <functional>
#include "lib.h" // error codes
#include "timer.h"
#include "loader.h"
#include "CStr.h"
// note: not thread-safe!
#include "loader.h"
// need to maintain this counter ourselves so we can reset after each load.
// need a persistent counter so we can reset after each load,
// and incrementally add "estimated/total".
static int progress_percent = 0;
// set by LDR_EndRegistering; used for progress % calculation. may be 0.
static double total_estimated_duration;
// main purpose is to indicate whether a load is in progress, so that
// LDR_ProgressiveLoad can return 0 iff loading just completed.
// the REGISTERING state allows us to detect 2 simultaneous loads (bogus).
@ -34,18 +43,17 @@ struct LoadRequest
void* param;
const CStrW description;
// rationale:
// rationale for storing as CStrW here:
// - needs to be wide because it's user-visible and will be translated.
// - don't just store a pointer - the caller's string may be volatile.
// - the module interface must work in C, so we get/set as wchar_t*.
int progress_percent_after_completion;
int estimated_duration_ms;
// LDR_Register gets these as parameters; pack everything together.
LoadRequest(LoadFunc func_, void* param_, const wchar_t* desc_, int pc_, int ms_)
LoadRequest(LoadFunc func_, void* param_, const wchar_t* desc_, int ms_)
: func(func_), param(param_), description(desc_),
progress_percent_after_completion(pc_), estimated_duration_ms(ms_)
estimated_duration_ms(ms_)
{
}
};
@ -53,6 +61,16 @@ struct LoadRequest
typedef std::deque<const LoadRequest> LoadRequests;
static LoadRequests load_requests;
// std::accumulate binary op; used by LDR_EndRegistering to sum up all
// estimated durations (for % progress calculation)
struct DurationAdder: public std::binary_function<double, const LoadRequest&, double>
{
double operator()(double partial_result, const LoadRequest& lr) const
{
return partial_result + lr.estimated_duration_ms*1e-3;
}
};
// call before starting to register load requests.
// this routine is provided so we can prevent 2 simultaneous load operations,
@ -74,21 +92,21 @@ int LDR_BeginRegistering()
// <param>: (optional) parameter/persistent state; must be freed by func.
// <description>: user-visible description of the current task, e.g.
// "Loading map".
// <progress_percent_after_completion>: optional; if non-zero, progress is
// set to this value after the current task completes.
// must increase monotonically.
// <estimated_duration_ms>: optional; if non-zero, this task will be
// postponed until the next LDR_ProgressiveLoad timeslice if there's not
// much time left. this reduces overruns of the timeslice => main loop is
// more responsive.
// <estimated_duration_ms>: used to calculate progress, and when checking
// whether there is enough of the time budget left to process this task
// (reduces timeslice overruns, making the main loop more responsive).
int LDR_Register(LoadFunc func, void* param, const wchar_t* description,
int progress_percent_after_completion, int estimated_duration_ms)
int estimated_duration_ms)
{
if(state != REGISTERING)
{
debug_warn("LDR_Register: not called between LDR_(Begin|End)Register - why?!");
// warn here instead of relying on the caller to CHECK_ERR because
// there will be lots of call sites spread around.
return -1;
}
const LoadRequest lr(func, param, description,
progress_percent_after_completion, estimated_duration_ms);
const LoadRequest lr(func, param, description, estimated_duration_ms);
load_requests.push_back(lr);
return 0;
}
@ -101,8 +119,12 @@ int LDR_EndRegistering()
if(state != REGISTERING)
return -1;
if(load_requests.empty())
debug_warn("LDR_EndRegistering: no LoadRequests queued");
state = LOADING;
progress_percent = 0;
total_estimated_duration = std::accumulate(load_requests.begin(), load_requests.end(), 0.0, DurationAdder());
return 0;
}
@ -128,16 +150,17 @@ int LDR_Cancel()
// tries to prevent starting a long task when at the end of a timeslice.
static bool HaveTimeForNextTask(double time_left, double time_budget, int estimated_duration_ms)
{
// have already exceeded our time budget => stop for now.
// have already exceeded our time budget
if(time_left <= 0.0)
return false;
// we've already used up more than 60%
// we've already used up more than 60%:
// (if it's less than that, we won't check the next task length)
if(time_left < 0.40*time_budget)
{
const double estimated_duration = estimated_duration_ms * 1e-3;
// .. next task is expected to be long - do it next call
// .. and the upcoming task is expected to be long -
// leave it for the next timeslice.
if(estimated_duration > time_left + time_budget*0.20)
return false;
}
@ -150,8 +173,9 @@ static bool HaveTimeForNextTask(double time_left, double time_budget, int estima
// <time_budget> [s]. if a request is lengthy, the budget may be exceeded.
// call from the main loop.
//
// passes back a description of the last task undertaken and the progress
// value established by the last request to complete.
// passes back a description of the next task that will be undertaken
// ("" if finished) and the progress value established by the
// last request to complete.
//
// return semantics:
// - if loading just completed, return 0.
@ -164,7 +188,7 @@ static bool HaveTimeForNextTask(double time_left, double time_budget, int estima
// persistent, we can't just store a pointer. returning a pointer to
// our copy of the description doesn't work either, since it's freed when
// the request is de-queued. that leaves writing into caller's buffer.
int LDR_ProgressiveLoad(double time_budget, wchar_t* current_description,
int LDR_ProgressiveLoad(double time_budget, wchar_t* description_,
size_t max_chars, int* progress_percent_)
{
// we're called unconditionally from the main loop, so this isn't
@ -173,22 +197,15 @@ int LDR_ProgressiveLoad(double time_budget, wchar_t* current_description,
return 1;
const double end_time = get_time() + time_budget;
int ret; // single exit; this is returned
// in case it's never set below (because all LoadRequests have
// progress_percent_after_completion = 0)
*progress_percent_ = progress_percent;
// (function will return immediately on failure or timeout)
while(!load_requests.empty())
{
const double time_left = end_time - get_time();
const LoadRequest& lr = load_requests.front();
// latch description of the current task now (it may be removed below)
wcscpy_s(current_description, max_chars, lr.description);
// do actual work of loading
int ret = lr.func(lr.param, time_left);
ret = lr.func(lr.param, time_left);
// .. either finished entirely, or failed => remove from queue
if(ret != ERR_TIMED_OUT)
load_requests.pop_front();
@ -197,26 +214,41 @@ int LDR_ProgressiveLoad(double time_budget, wchar_t* current_description,
// rationale: bail immediately instead of remembering the first error
// that came up, so that we report can all errors that happen.
if(ret != 0)
return ret;
// .. completed normally:
// update progress
const int new_pc = lr.progress_percent_after_completion;
if(new_pc)
goto done;
// .. completed normally => update progress
// note: during development, estimates won't yet be set,
// so allow this to be 0 and don't fail in LDR_EndRegistering
if(total_estimated_duration != 0.0) // prevent division by zero
{
assert(new_pc > progress_percent);
*progress_percent_ = progress_percent = new_pc;
const double fraction = lr.estimated_duration_ms*1e-3 / total_estimated_duration;
progress_percent += (int)(fraction * 100.0);
assert(0 <= progress_percent && progress_percent <= 100);
}
// check if we're out of time; take into account next task length.
// note: do this at the end of the loop to make sure there's
// progress even if the timer is low-resolution (=> time_left = 0).
if(!HaveTimeForNextTask(time_left, time_budget, lr.estimated_duration_ms))
return ERR_TIMED_OUT;
{
ret = ERR_TIMED_OUT;
goto done;
}
}
// queue is empty, we just finished.
state = IDLE;
assert(progress_percent == 100);
return 0;
ret = 0;
// set output params (there are several return points above)
done:
*progress_percent_ = progress_percent;
// we want the next task, instead of what just completed:
// it will be displayed during the next load phase.
const wchar_t* description = L""; // assume finished
if(!load_requests.empty())
description = load_requests.front().description.c_str();
wcscpy_s(description_, max_chars, description);
return ret;
}

45
source/ps/Loader.h
View File

@ -1,3 +1,24 @@
// FIFO queue of load 'functors' with time limit; enables displaying
// load progress without resorting to threads (complicated).
//
// Jan Wassenberg, initial implementation finished 2005-03-21
// jan@wildfiregames.com
// intended use:
// replace the InitEverything function with the following:
// LDR_BeginRegistering()
// LDR_Register() for each sub-function (*)
// LDR_EndRegistering()
// then in the main loop, call LDR_ProgressiveLoad().
//
// *: splitting up InitEverything is required so that control returns to
// the main loop occasionally; that allows displaying the progress.
// note that we can't interrupt loading without threads (complex).
//
// this module is not thread-safe!
#include <wchar.h>
@ -21,34 +42,34 @@ extern int LDR_BeginRegistering();
typedef int (*LoadFunc)(void* param, double time_left);
// register a load request (later processed in FIFO order).
// <func>: function that will perform the actual work; see LoadFunc above.
// <func>: function that will perform the actual work; see LoadFunc.
// <param>: (optional) parameter/persistent state; must be freed by func.
// <description>: user-visible description of the current task, e.g.
// "Loading map".
// <progress_percent_after_completion>: optional; if non-zero, progress is
// set to this value after the current task completes.
// must increase monotonically.
// <estimated_duration_ms>: optional; if non-zero, this task will be
// postponed until the next LDR_ProgressiveLoad timeslice if there's not
// much time left. this reduces overruns of the timeslice => main loop is
// more responsive.
// <estimated_duration_ms>: used to calculate progress, and when checking
// whether there is enough of the time budget left to process this task
// (reduces timeslice overruns, making the main loop more responsive).
extern int LDR_Register(LoadFunc func, void* param, const wchar_t* description,
int progress_percent_after_completion = 0, int estimated_duration_ms = 0);
int estimated_duration_ms);
// call when finished registering load requests; subsequent calls to
// LDR_ProgressiveLoad will then work off the queued entries.
extern int LDR_EndRegistering();
// immediately cancel the load. note: no special notification will be
// returned by LDR_ProgressiveLoad.
extern int LDR_Cancel();
// process as many of the queued load requests as possible within
// <time_budget> [s]. if a request is lengthy, the budget may be exceeded.
// call from the main loop.
//
// passes back a description of the last task undertaken and the progress
// value established by the last request to complete.
// passes back a description of the next task that will be undertaken
// ("" if finished) and the progress value established by the
// last request to complete.
//
// return semantics:
// - if loading just completed, return 0.
@ -61,5 +82,5 @@ extern int LDR_Cancel();
// persistent, we can't just store a pointer. returning a pointer to
// our copy of the description doesn't work either, since it's freed when
// the request is de-queued. that leaves writing into caller's buffer.
extern int LDR_ProgressiveLoad(double time_budget, wchar_t* current_description,
extern int LDR_ProgressiveLoad(double time_budget, wchar_t* next_description,
size_t max_chars, int* progress_percent);