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Block-Flow: implement cyclic usage of an extent pool

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..with the ability to grow on demand..
..possibly add the new extents in the middle, by first allocating at the end
  and then using the std::rotate() algo to bring them to the point
  in the middle where new extents are required
This commit is contained in:
Fischlurch 2023-07-10 05:40:50 +02:00
parent c1b16349f2
commit e86cb017a5
2 changed files with 137 additions and 22 deletions
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96
src/vault/mem/extent-family.hpp
View file

@ -32,7 +32,7 @@
** and down to avoid holding larger amounts of unused memory, while the availability
** of a baseline amount of memory can be enforced.
**
** @see ////TODO_test usage example
** @see ExtentFamily_test
** @see gear::BlockFlow usage example
**
** @todo WIP-WIP-WIP 7/2023 »Playback Vertical Slice«
@ -51,6 +51,7 @@
//#include "lib/util.hpp"
//#include <string>
#include <algorithm>
#include <memory>
#include <vector>
#include <array>
@ -68,12 +69,17 @@ namespace mem {
/**
* Memory manager to provide a sequence of Extents for cyclic usage.
* @todo WIP-WIP 7/2023
* @see NA_test
* @see ExtentFamily_test
*/
template<typename T, size_t siz>
class ExtentFamily
: util::NonCopyable
{
/** number of excess new extents
* to add whenever new storage is required
*/
static const size_t EXCESS_ALLOC{5};
public:
struct Extent
: std::array<T,siz>
@ -108,6 +114,8 @@ namespace mem {
using RawIter = typename Extents::iterator;
/* ==== Management Data ==== */
Extents extents_;
size_t start_,after_;
@ -125,17 +133,42 @@ namespace mem {
extents_.reserve (expectedMaxExtents);
}
/** claim next \a cnt extents, possibly allocate.
* @note always allocating slightly in excess
*/
void
openNew (size_t cnt)
{
UNIMPLEMENTED ("claim next cnt extents, possibly allocate");
if (not canAccomodate (cnt))
{//insufficient reserve -> allocate
size_t oldSiz = extents_.size();
size_t addSiz = cnt - freeSlotCnt()
+ EXCESS_ALLOC;
// add a strike of new extents at the end
extents_.resize (oldSiz + addSiz);
if (isWrapped())
{// need the new elements in the middle, before the existing start_
auto p = extents_.begin();
auto first = p + start_;
auto mid = p + oldSiz;
auto last = p + oldSiz + addSiz;
// relocate [fist..mid) after [mid..last)
std::rotate (first, mid, last);
start_ += addSiz;
}
}
// now sufficient reserve extents are available
ENSURE (canAccomodate (cnt));
incWrap (after_, cnt);
}
/** discard oldest \a cnt extents */
void
dropOld (size_t cnt)
{
UNIMPLEMENTED ("discard oldest cnt extents");
}
REQUIRE (cnt <= activeSlotCnt());
incWrap (start_, cnt);
} ////////////////////////////////////////////////////////////////////////////TICKET #1316 : should reduce excess allocation (with apropriate damping to avoid oscillations)
/** allow transparent iteration of Extents, expanding storage on demand */
@ -149,6 +182,49 @@ namespace mem {
}
private:
bool
isWrapped() const
{
return after_ < start_;
} // note: both are equal only when empty
/** @return number of allocated slots actually used */
size_t
activeSlotCnt() const
{
REQUIRE (start_ <= extents_.size());
REQUIRE (after_ <= extents_.size());
return not isWrapped()? after_ - start_
: (after_ - 0)
+(extents_.size() - start_);
}
size_t
freeSlotCnt() const
{ // always keep one in reserve...
REQUIRE (activeSlotCnt() < extents_.size());
return extents_.size() - activeSlotCnt();
}
bool
canAccomodate (size_t addCnt) const
{
return addCnt < freeSlotCnt(); // keep one in reserve
}
/** increment index, but wrap at array end.
* @remark using the array cyclically
*/
void
incWrap (size_t& idx, size_t inc)
{
idx = (idx+inc) % extents_.size();
}
/* == Iteration control API (used by IterAdapter via ADL) == */
friend bool
@ -163,11 +239,19 @@ namespace mem {
UNIMPLEMENTED ("ExtentFamily iteration control: access next Extent, possibly expand allocation");
}
/// „backdoor“ to watch internals from tests
friend class ExtentDiagnostic<T,siz>;
};
/* ===== Test / Diagnostic ===== */
template<typename T, size_t siz>
struct ExtentDiagnostic
{
@ -178,7 +262,7 @@ namespace mem {
size_t first() { return exFam_.start_; }
size_t last() { return exFam_.after_; }
size_t size() { return exFam_.extents_.size(); }
size_t active() { UNIMPLEMENTED ("count active"); }
size_t active() { return exFam_.activeSlotCnt(); }
};
template<typename T, size_t siz>

63
wiki/thinkPad.ichthyo.mm
View file

@ -78517,8 +78517,8 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
<node COLOR="#338800" CREATED="1688434743454" ID="ID_722620082" MODIFIED="1688434762609" TEXT="ExtentFamily erzeugen mit pre-Allocation">
<icon BUILTIN="button_ok"/>
</node>
<node BACKGROUND_COLOR="#eef0c5" COLOR="#990000" CREATED="1688862941032" ID="ID_1514279635" MODIFIED="1688868055421" TEXT="Diagnose der tats&#xe4;chlichen Speicherbelegung">
<icon BUILTIN="pencil"/>
<node COLOR="#338800" CREATED="1688862941032" ID="ID_1514279635" MODIFIED="1688960119406" TEXT="Diagnose der tats&#xe4;chlichen Speicherbelegung">
<icon BUILTIN="button_ok"/>
</node>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1688863035539" ID="ID_557979292" MODIFIED="1688864962621" TEXT="belegen und Aufr&#xe4;umen">
@ -78783,8 +78783,8 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1688337270626" ID="ID_1810148055" MODIFIED="1688337284937" TEXT="&#xbb;BlockFlow&#xab; : Implementation">
<icon BUILTIN="flag-yellow"/>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1688398675985" ID="ID_291772625" MODIFIED="1688398683406" TEXT="Basis: ExtentFamily">
<icon BUILTIN="flag-yellow"/>
<node BACKGROUND_COLOR="#eef0c5" COLOR="#990000" CREATED="1688398675985" ID="ID_291772625" MODIFIED="1688960090391" TEXT="Basis: ExtentFamily">
<icon BUILTIN="pencil"/>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1688398685028" ID="ID_1348599303" MODIFIED="1688398807927" TEXT="Anforderungen">
<icon BUILTIN="yes"/>
<node CREATED="1688398688699" ID="ID_1432998672" MODIFIED="1688398701914" TEXT="stellt eine Sequenz von &#xbb;Extents&#xab; bereit"/>
@ -78808,9 +78808,9 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
<icon BUILTIN="hourglass"/>
</node>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1688398813243" ID="ID_504623704" MODIFIED="1688398863035" TEXT="Aufbau testgetrieben...">
<node BACKGROUND_COLOR="#eef0c5" COLOR="#990000" CREATED="1688398813243" ID="ID_504623704" MODIFIED="1688960080656" TEXT="Aufbau testgetrieben...">
<arrowlink COLOR="#eb4070" DESTINATION="ID_1132827905" ENDARROW="Default" ENDINCLINATION="-593;73;" ID="Arrow_ID_709934622" STARTARROW="None" STARTINCLINATION="-214;-18;"/>
<icon BUILTIN="flag-yellow"/>
<icon BUILTIN="pencil"/>
<node COLOR="#338800" CREATED="1688398884005" ID="ID_1188543253" MODIFIED="1688867997850" TEXT="Basis-Struktur">
<icon BUILTIN="button_ok"/>
<node CREATED="1688432746255" ID="ID_880122043" MODIFIED="1688432851088" TEXT="Entscheidung: die Gr&#xf6;&#xdf;e ist eine compile-time-Konstante">
@ -78949,18 +78949,49 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
</node>
</node>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1688398893220" ID="ID_675575195" MODIFIED="1688398901316" TEXT="belegen / freigeben">
<icon BUILTIN="flag-yellow"/>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1688437691137" ID="ID_292063242" MODIFIED="1688437712023" TEXT="pr&#xfc;fen auf ausreichende Reserve">
<icon BUILTIN="flag-yellow"/>
<node COLOR="#338800" CREATED="1688398893220" ID="ID_675575195" MODIFIED="1688960070966" TEXT="belegen / freigeben">
<icon BUILTIN="button_ok"/>
<node COLOR="#338800" CREATED="1688952897933" ID="ID_832611581" MODIFIED="1688955651916" TEXT="freie Reserve ermitteln">
<icon BUILTIN="button_ok"/>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1688437762175" ID="ID_1456790340" MODIFIED="1688437794274" TEXT="sonst: Allokation erweitern">
<icon BUILTIN="flag-yellow"/>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1688437770295" ID="ID_867206595" MODIFIED="1688437792757" TEXT="falls am Ende">
<icon BUILTIN="flag-yellow"/>
<node COLOR="#338800" CREATED="1688437691137" ID="ID_292063242" MODIFIED="1688960068981" TEXT="pr&#xfc;fen auf ausreichende Reserve">
<icon BUILTIN="button_ok"/>
</node>
<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1688437784470" ID="ID_797852741" MODIFIED="1688437792758" TEXT="falls wrap-around">
<icon BUILTIN="flag-yellow"/>
<node COLOR="#338800" CREATED="1688437762175" ID="ID_1456790340" MODIFIED="1688960067652" TEXT="sonst: Allokation erweitern">
<icon BUILTIN="button_ok"/>
<node COLOR="#338800" CREATED="1688437770295" ID="ID_867206595" MODIFIED="1688960066248" TEXT="falls am Ende">
<icon BUILTIN="button_ok"/>
<node CREATED="1688957825760" ID="ID_376842621" MODIFIED="1688957834883" TEXT="vector::resize() gen&#xfc;gt"/>
</node>
<node COLOR="#338800" CREATED="1688437784470" ID="ID_797852741" MODIFIED="1688960065205" TEXT="falls wrap-around">
<icon BUILTIN="button_ok"/>
<node CREATED="1688957839759" ID="ID_671792490" MODIFIED="1688957862703" TEXT="zus&#xe4;tzlich die neuen Elemente in die Pufferzone in der Mitte rotieren"/>
<node CREATED="1688957863500" ID="ID_592181743" MODIFIED="1688958053349" TEXT="std::rotate() verwenden">
<richcontent TYPE="NOTE"><html>
<head>
</head>
<body>
<p>
...dieser tauscht per std::swap aus; und zwar rekursiv inkrementell: erst das Segment vom Ende an den Anfang und dann rekursiv wieder std::rotate f&#252;r den Rest. Komplexit&#228;t: linear
</p>
</body>
</html></richcontent>
</node>
</node>
</node>
<node BACKGROUND_COLOR="#d2beaf" COLOR="#5c4d6e" CREATED="1688958797642" ID="ID_205839494" MODIFIED="1688958807300" TEXT="&#xdc;berschu&#xdf; freigeben">
<icon BUILTIN="hourglass"/>
<node BACKGROUND_COLOR="#fdfdcf" COLOR="#ff0000" CREATED="1688958808347" ID="ID_1777900061" MODIFIED="1688958867924" TEXT="Gefahr von Oszillationen &#x27f9; vorerst noch nicht implementiert">
<icon BUILTIN="messagebox_warning"/>
<node BACKGROUND_COLOR="#e0ceaa" COLOR="#690f14" CREATED="1688958965134" ID="ID_559031085" MODIFIED="1688958983164" TEXT="vorerst w&#xe4;chst die Allokation nur">
<icon BUILTIN="clanbomber"/>
</node>
</node>
<node BACKGROUND_COLOR="#d2beaf" COLOR="#5c4d6e" CREATED="1688958894805" ID="ID_1746833075" MODIFIED="1688958904528" TEXT="#1316 regulate Scheduler memory allocation">
<icon BUILTIN="hourglass"/>
<node CREATED="1688958915756" ID="ID_292339303" MODIFIED="1688958930662" TEXT="man m&#xfc;&#xdf;te einen typischen / durchschnittlichen Bedarf etablieren"/>
<node CREATED="1688958931778" ID="ID_764223223" MODIFIED="1688958942454" TEXT="und dann mit einer gewissen D&#xe4;mpfung darauf hinsteuern"/>
</node>
</node>
</node>