AceTime
0.1
Date and time classes for Arduino that supports the TZ DAtabase, and a system clock synchronized from an NTP server or an RTC chip.
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A heap manager which is specialized and tuned to manage a collection of Transitions, keeping track of unused, used, and active states, using a fixed array of Transitions. More...
#include <ExtendedZoneSpecifier.h>
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TransitionStorage () | |
Constructor. More... | |
void | init () |
Initialize all pools. More... | |
Transition * | getPrior () |
Return the current prior transition. More... | |
void | swap (Transition **a, Transition **b) |
Swap 2 transitions. More... | |
void | resetCandidatePool () |
Empty the Candidate pool by resetting the various indexes. More... | |
Transition ** | getCandidatePoolBegin () |
Transition ** | getCandidatePoolEnd () |
Transition ** | getActivePoolBegin () |
Transition ** | getActivePoolEnd () |
Transition * | getFreeAgent () |
Return a pointer to the first Transition in the free pool. More... | |
void | addFreeAgentToActivePool () |
Immediately add the free agent Transition at index mIndexFree to the Active pool. More... | |
Transition ** | reservePrior () |
Allocate one Transition just after the Active pool, but before the Candidate pool, to keep the most recent prior Transition. More... | |
void | setFreeAgentAsPrior () |
Swap the Free agrent transition with the current Prior transition. More... | |
void | addPriorToCandidatePool () |
Add the current prior into the Candidates pool. More... | |
void | addFreeAgentToCandidatePool () |
Add the free agent Transition at index mIndexFree to the Candidate pool, sorted by transitionTime. More... | |
void | addActiveCandidatesToActivePool () |
Add active candidates into the Active pool, and collapse the Candidate pool. | |
const Transition * | findTransition (acetime_t epochSeconds) const |
Return the Transition matching the given epochSeconds. More... | |
const Transition * | findTransitionForDateTime (const LocalDateTime &ldt) const |
Return the Transition matching the given dateTime. More... | |
void | log () const |
Verify that the indexes are valid. More... | |
void | resetHighWater () |
Reset the high water mark. More... | |
uint8_t | getHighWater () const |
Return the high water mark. More... | |
A heap manager which is specialized and tuned to manage a collection of Transitions, keeping track of unused, used, and active states, using a fixed array of Transitions.
Its main purpose is to provide some illusion of dynamic memory allocation without actually performing any dynamic memory allocation.
We create a fixed sized array for the total pool, determined by the template parameter SIZE, then manage the various sub-pools of Transition objects. The allocation of the various sub-pools is intricately tied to the precise pattern of creation and release of the various Transition objects within the ExtendedZoneSpecifier class.
There are 4 pools indicated by the following half-open (exclusive) index ranges:
1) Active pool: [0, mIndexPrior) 2) Prior pool: [mIndexPrior, mIndexCandidates), either 0 or 1 element 3) Candidate pool: [mIndexCandidates, mIndexFree) 4) Free pool: [mIndexFree, SIZE)
At the completion of the ExtendedZoneSpecifier::init(LocalDate& ld) method, the Active pool will contain the active Transitions relevant to the 'year' defined by the LocalDate. The Prior and Candidate pools will be empty, with the Free pool taking up the remaining space.
Definition at line 330 of file ExtendedZoneSpecifier.h.
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Constructor.
Definition at line 333 of file ExtendedZoneSpecifier.h.
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Immediately add the free agent Transition at index mIndexFree to the Active pool.
Then increment mIndexFree to remove the free agent from the Free pool. This assumes that the Pending and Candidate pool are empty, which makes the Active pool come immediately before the Free pool.
Definition at line 404 of file ExtendedZoneSpecifier.h.
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Add the free agent Transition at index mIndexFree to the Candidate pool, sorted by transitionTime.
Then increment mIndexFree by one to remove the free agent from the Free pool.
Definition at line 441 of file ExtendedZoneSpecifier.h.
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Add the current prior into the Candidates pool.
Prior is always just before the start of the Candidate pool, so we just need to shift back the start index of the Candidate pool.
Definition at line 432 of file ExtendedZoneSpecifier.h.
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Return the Transition matching the given epochSeconds.
Return nullptr if no matching Transition found.
Definition at line 481 of file ExtendedZoneSpecifier.h.
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Return the Transition matching the given dateTime.
Return nullptr if no matching Transition found. During DST changes, a particlar LocalDateTime may correspond to 2 Transitions or 0 Transitions, and there are potentially multiple ways to handle this. This method implements the following algorithm:
1) If the localDateTime falls in the DST transition gap where 0 Transitions ought to be found, e.g. between 02:00 and 03:00 in America/Los_Angeles when standard time switches to DST time), the immediate prior Transition is returned (in effect extending the UTC offset of the prior Transition through the gap. For example, when DST starts, 02:00 becomes 03:00, so a time of 02:30 does not exist, but the Transition returned will be the one valid at 01:59. When it is converted to epoch_seconds and converted back to a LocalDateTime, the 02:30 time will become 03:30, since the later UTC offset will be used.
2) If the localDateTime falls in a time period where there are 2 Transitions, hence 2 valid UTC offsets, the later Transition is returned. For example, when DST ends in America/Los_Angeles, 02:00 becomes 01:00, so a time of 01:30 could belong to the earlier or later Transition. This method returns the later Transition.
Definition at line 520 of file ExtendedZoneSpecifier.h.
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Return a pointer to the first Transition in the free pool.
If this transition is not used, then it's ok to just drop it. The next time getFreeAgent() is called, the same Transition will be returned.
Definition at line 383 of file ExtendedZoneSpecifier.h.
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Return the high water mark.
This is the largest value of mIndexFree that was used. If this returns SIZE, it indicates that the Transition mPool overflowed. For debugging.
Definition at line 576 of file ExtendedZoneSpecifier.h.
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Return the current prior transition.
Definition at line 346 of file ExtendedZoneSpecifier.h.
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Initialize all pools.
Definition at line 336 of file ExtendedZoneSpecifier.h.
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Verify that the indexes are valid.
Used only for debugging.
Definition at line 542 of file ExtendedZoneSpecifier.h.
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Allocate one Transition just after the Active pool, but before the Candidate pool, to keep the most recent prior Transition.
Shift the Candidate pool and Free pool up by one.
Definition at line 416 of file ExtendedZoneSpecifier.h.
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Empty the Candidate pool by resetting the various indexes.
If every iteration of findTransitionsForMatch() finishes with addFreeAgentToActivePool() or addActiveCandidatesToActivePool(), it may be possible to remove this. But it's safer to reset the indexes upon each iteration.
Definition at line 363 of file ExtendedZoneSpecifier.h.
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Swap the Free agrent transition with the current Prior transition.
Definition at line 423 of file ExtendedZoneSpecifier.h.
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Swap 2 transitions.
Definition at line 349 of file ExtendedZoneSpecifier.h.