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Comment:Support using a hash table unless a really small input is used (may change in the future?)
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SHA3-256: 37d00c3cfb7a3c585d67153b63259f7031a1ae75c050d3191cd0cf3f52b39a6a
User & Date: rkeene on 2019-11-04 21:09:26
Other Links: manifest | tags
Context
2019-11-04
21:16
Minor hash table optimization check-in: 3c8c52a9f8 user: rkeene tags: trunk
21:09
Support using a hash table unless a really small input is used (may change in the future?) check-in: 37d00c3cfb user: rkeene tags: trunk
2019-10-10
00:40
Improved and parameterized perfect hash function generator check-in: f615eecc64 user: rkeene tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Modified lib/xvfs/xvfs.c.rvt from [6833d26c3e] to [ced159acac].

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<?
	package require xvfs

	xvfs::main $::xvfs::argv

?>
static long xvfs_<?= $::xvfs::fsName ?>_nameToIndex(const char *path) {












	long pathIndex;
	ssize_t pathLen;

	if (path == NULL) {
		return(XVFS_NAME_LOOKUP_ERROR);
	}

	pathLen = strlen(path);




	pathIndex = <?= [::xvfs::generatePerfectHashFunctionCall "path" pathLen XVFS_NAME_LOOKUP_ERROR $::xvfs::outputFiles] ?>;
	if (pathIndex < 0 || pathIndex >= <?= [llength $::xvfs::outputFiles] ?>) {
		pathIndex = XVFS_NAME_LOOKUP_ERROR;
	}

	if (pathIndex != XVFS_NAME_LOOKUP_ERROR) {
		if (strcmp(path, xvfs_<?= $::xvfs::fsName ?>_data[pathIndex].name) == 0) {
			return(pathIndex);
		}
	}



	

	return(XVFS_NAME_LOOKUP_ERROR);
}

static const char **xvfs_<?= $::xvfs::fsName ?>_getChildren(const char *path, Tcl_WideInt *count) {
	const struct xvfs_file_data *fileInfo;
	long inode;









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<?
	package require xvfs

	xvfs::main $::xvfs::argv

?>
static long xvfs_<?= $::xvfs::fsName ?>_nameToIndex(const char *path) {
<?
		if {[llength $::xvfs::outputFiles] < 3} {
			set hashMode perfectHashFunction
		} else {
			set hashMode hashTable
		}

		if {$hashMode eq "hashTable"} {
			set hashTable [::xvfs::generateHashTable pathIndex path pathLen XVFS_NAME_LOOKUP_ERROR $::xvfs::outputFiles prefix "\t" hashTableSize 30 validate "strcmp(path, xvfs_${::xvfs::fsName}_data\[pathIndex\].name) == 0" onValidated "return(pathIndex);"]
			set hashTableHeader [dict get $hashTable header]
			puts $hashTableHeader
		}
?>	long pathIndex;
	ssize_t pathLen;

	if (path == NULL) {
		return(XVFS_NAME_LOOKUP_ERROR);
	}

	pathLen = strlen(path);

<?
		if {$hashMode eq "perfectHashFunction"} {
?>
	pathIndex = <?= [::xvfs::generatePerfectHashFunctionCall "path" pathLen XVFS_NAME_LOOKUP_ERROR $::xvfs::outputFiles] ?>;
	if (pathIndex < 0 || pathIndex >= <?= [llength $::xvfs::outputFiles] ?>) {
		pathIndex = XVFS_NAME_LOOKUP_ERROR;
	}

	if (pathIndex != XVFS_NAME_LOOKUP_ERROR) {
		if (strcmp(path, xvfs_<?= $::xvfs::fsName ?>_data[pathIndex].name) == 0) {
			return(pathIndex);
		}
	}
<?
		} else {
			puts [dict get $hashTable body]
		}
?>
	return(XVFS_NAME_LOOKUP_ERROR);
}

static const char **xvfs_<?= $::xvfs::fsName ?>_getChildren(const char *path, Tcl_WideInt *count) {
	const struct xvfs_file_data *fileInfo;
	long inode;
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Modified lib/xvfs/xvfs.tcl from [1ce5b335aa] to [74213d3431].

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}

proc ::xvfs::staticIncludeHeader {pathToHeaderFile} {
	set fd [open $pathToHeaderFile]
	::xvfs::staticIncludeHeaderData [read $fd]
	close $fd
}
























































proc ::xvfs::generatePerfectHashFunctionCall {cVarName cVarLength invalidValue nameList args} {


	array set config {

		preferMinimalHashSize   8
		switchToNonMinimalHash  1048576
		triesAtHashSize         1024
		maxIntermediateMultiple 8
	}



	foreach {configKey configVal} $args {
		if {![info exists config($configKey)]} {
			error "Invalid option: $configKey"
		}
	}
	array set config $args

	set minVal 0
	set maxVal [llength $nameList]

	set testExpr(0) {([zlib adler32 $nameItem $alpha] + $beta) % $gamma}
	set testExpr(1) {([zlib crc32 $nameItem $alpha] + $beta) % $gamma}
	set testExpr(2) {([zlib adler32 $nameItem [zlib crc32 $nameItem $alpha]] + $beta) % $gamma}

	set testExprC(0) {((Tcl_ZlibAdler32(${alpha}LU, (unsigned char *) $cVarName, $cVarLength) + ${beta}LU) % ${gamma}LU)}
	set testExprC(1) {((Tcl_ZlibCRC32(${alpha}LU, (unsigned char *) $cVarName, $cVarLength) + ${beta}LU) % ${gamma}LU)}
	set testExprC(2) {((Tcl_ZlibAdler32(Tcl_ZlibCRC32(${alpha}LU, (unsigned char *) $cVarName, $cVarLength), (unsigned char *) $cVarName, $cVarLength) + ${beta}LU) % ${gamma}LU)}

	set minimal false
	if {$maxVal < $config(preferMinimalHashSize)} {

		set minimal true
	}




	set round -1


	set gammaRoundMod [expr {$maxVal * ($config(maxIntermediateMultiple) - 1)}]

	while true {
		if {$minimal && $round > $config(switchToNonMinimalHash)} {

			set minimal false

			set round -1

		}
		incr round

		if {$minimal} {
			set gamma [expr {$maxVal + ($round % ($maxVal * 4))}]
		} else {
			set gamma [expr {$maxVal + ($round % $gammaRoundMod)}]
		}



		for {set try 0} {$try < $config(triesAtHashSize)} {incr try} {
			set alpha [expr {entier(rand() * (2**31))}]
			set beta  [expr {entier(rand() * (2**31))}]

			foreach {testExprID testExprContents} [array get testExpr] {
				set idx -1
				set seenIndexes [list]
				set failed false
				foreach nameItem $nameList {

					set testExprVal [expr $testExprContents]




					if {$minimal} {
						incr idx

						if {$testExprVal != $idx} {
							set failed true
							break
						}
					} else {
						if {$testExprVal in $seenIndexes} {
							set failed true
							break
						}







						lappend seenIndexes $testExprVal
					}
				}



				if {!$failed} {
					break
				}
			}

			if {!$failed} {
				break
			}
		}

		if {!$failed} {
			break
		}
	}

	if {$minimal} {
		set phfCall [subst $testExprC($testExprID)]
	} else {







		unset -nocomplain mapArray
		for {set idx 0} {$idx < $gamma} {incr idx} {
			set mapArray($idx) $invalidValue



		}








		set idx -1
		foreach nameItem $nameList {
			incr idx

			set mapArray([expr $testExpr($testExprID)]) $idx



		}

		set map "(long\[\])\{"
		for {set idx 0} {$idx < $gamma} {incr idx} {
			append map "$mapArray($idx), "


		}
		set map [string range $map 0 end-2]
		append map "\}\[[subst $testExprC($testExprID)]\]"

		set phfCall $map
	}


	return $phfCall
}





















































































package provide xvfs 1









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}

proc ::xvfs::staticIncludeHeader {pathToHeaderFile} {
	set fd [open $pathToHeaderFile]
	::xvfs::staticIncludeHeaderData [read $fd]
	close $fd
}

proc ::xvfs::_tryFit {list} {
	set idx -1
	set lastItem -100000
	foreach item $list {
		incr idx

		if {$item <= $lastItem} {
			return ""
		}

		set difference [expr {$item - $idx}]
		if {$idx != 0} {
			set divisor [expr {$item / $idx}]
		} else {
			set divisor 1
		}
		lappend differences $difference
		lappend divisors $divisor

		set lastItem $item
	}

	foreach divisor [lrange $divisors 1 end] {
		incr divisorCount
		incr divisorValue $divisor
	}
	set divisor [expr {$divisorValue / $divisorCount}]

	for {set i 0} {$i < [llength $list]} {incr i} {
		lappend outList $i
	}

	set mapFunc " - ${difference}"

	set newList [lmap v $list { expr "\$v${mapFunc}" }]
	if {$newList eq $outList} {
		return $mapFunc
	}

	if {$divisor != 1} {
		set mapFunc " / ${divisor}"
		set newList [lmap v $list { expr "\$v${mapFunc}" }]
		if {$newList eq $outList} {
			return $mapFunc
		}

		set subMapFunc [_tryFit $newList]
		if {$subMapFunc != ""} {
			return " / ${divisor}${subMapFunc}"
		}
	}

	return ""
}

proc ::xvfs::generatePerfectHashFunctionCall {cVarName cVarLength invalidValue nameList args} {
	# Manage config
	## Default config
	array set config {
		useCacheFirst  false
		cacheValue     true

		enableCache    false

	}
	set config(cacheFile) [file join [file normalize ~/.cache] xvfs phf-cache.db]

	## User config
	foreach {configKey configVal} $args {
		if {![info exists config($configKey)]} {
			error "Invalid option: $configKey"
		}
	}
	array set config $args

	if {$config(enableCache)} {
		package require sqlite3
	}


	# Adjustment for computing the expense of a function call by its length
	# Calls that take longer should be made longer, so make CRC32 longer
	# than Adler32
	set lengthAdjustment [list Tcl_ZlibCRC32 Tcl_CRCxxx32]


	# Check for a cached entry
	if {$config(enableCache) && $config(useCacheFirst)} {
		catch {
			set hashKey $nameList

			sqlite3 ::xvfs::phfCache $config(cacheFile)
			::xvfs::phfCache eval {CREATE TABLE IF NOT EXISTS cache(hashKey PRIMARY KEY, function BLOB);}
			::xvfs::phfCache eval {SELECT function FROM cache WHERE hashKey = $hashKey LIMIT 1;} cacheRow {}
		}
		catch {
			::xvfs::phfCache close
		}




		if {[info exists cacheRow(function)]} {
			set phfCall $cacheRow(function)
			set phfCall [string map [list @@CVARNAME@@ $cVarName @@CVARLENGTH@@ $cVarLength @@INVALIDVALUE@@ $invalidValue] $phfCall]

			return $phfCall
		}

	}





	set minVal 0
	set maxVal [llength $nameList]
	set testExpr_(0) {[zlib adler32 $nameItem $alpha] % $gamma}



	set testExpr(1) {[zlib crc32 $nameItem $alpha] % $gamma}
	set testExpr_(2) {[zlib adler32 $nameItem [zlib crc32 $nameItem $alpha]] % $gamma}



	set testExpr_(3) {[zlib crc32 $nameItem [zlib adler32 $nameItem $alpha]] % $gamma}
	set testExprC(0) {((Tcl_ZlibAdler32(${alpha}LU, (unsigned char *) @@CVARNAME@@, @@CVARLENGTH@@) % ${gamma}LU)${fitMod})}
	set testExprC(1) {((Tcl_ZlibCRC32(${alpha}LU, (unsigned char *) @@CVARNAME@@, @@CVARLENGTH@@) % ${gamma}LU)${fitMod})}
	set testExprC(2) {((Tcl_ZlibAdler32(Tcl_ZlibCRC32(${alpha}LU, (unsigned char *) @@CVARNAME@@, @@CVARLENGTH@@), (unsigned char *) @@CVARNAME@@, @@CVARLENGTH@@) % ${gamma}LU)${fitMod})}
	set testExprC(3) {((Tcl_ZlibCRC32(Tcl_ZlibAdler32(${alpha}LU, (unsigned char *) @@CVARNAME@@, @@CVARLENGTH@@), (unsigned char *) @@CVARNAME@@, @@CVARLENGTH@@) % ${gamma}LU)${fitMod})}

	# Short-circuit for known cases
	if {$maxVal == 1} {
		return 0
	}

	set round -1




	while true {
		incr round

		set gamma [expr {$maxVal + ($round % ($maxVal * 128))}]
		set alpha [expr {$round / 6}]

		foreach {testExprID testExprContents} [array get testExpr] {
			set unFitList [list]
			foreach nameItem $nameList {
				set testExprVal [expr $testExprContents]
				lappend unFitList $testExprVal
			}

			set failed false
			set fitMod [_tryFit $unFitList]
			if {$fitMod eq ""} {
				set failed true


			}

			if {!$failed} {
				break
			}
		}

		if {!$failed} {
			break
		}

	}

	set phfCall [string map [list { - 0LU} ""] [subst $testExprC($testExprID)]]

	# Check cache for a better answer
	if {$config(enableCache)} {
		catch {
			set hashKey $nameList
			set cacheDir [file dirname $config(cacheFile)]
			file mkdir $cacheDir

			unset -nocomplain cacheRow


			sqlite3 ::xvfs::phfCache $config(cacheFile)
			::xvfs::phfCache eval {CREATE TABLE IF NOT EXISTS cache(hashKey PRIMARY KEY, function BLOB);}
			::xvfs::phfCache eval {SELECT function FROM cache WHERE hashKey = $hashKey LIMIT 1;} cacheRow {}

			set updateCache false
			if {[info exists cacheRow(function)]} {
				if {[string length [string map $lengthAdjustment $cacheRow(function)]] <= [string length [string map $lengthAdjustment $phfCall]]} {
					# Use the cached value since it is better
					set phfCall $cacheRow(function)
				} else {
					set updateCache true
				}
			} else {
				set updateCache true

			}

			if {$updateCache && $config(cacheValue)} {
				# Save to cache
				::xvfs::phfCache eval {INSERT OR REPLACE INTO cache (hashKey, function) VALUES ($hashKey, $phfCall);}
			}
		}



		catch {
			::xvfs::phfCache close
		}


	}


	set phfCall [string map [list @@CVARNAME@@ $cVarName @@CVARLENGTH@@ $cVarLength @@INVALIDVALUE@@ $invalidValue] $phfCall]

	return $phfCall
}

proc ::xvfs::generateHashTable {outCVarName cVarName cVarLength invalidValue nameList args} {
	# Manage config
	## Default config
	array set config {
		prefix        ""
		hashTableSize 10
		validate      0
		onValidated   "break;"
	}

	## User config
	foreach {configKey configVal} $args {
		if {![info exists config($configKey)]} {
			error "Invalid option: $configKey"
		}
	}
	array set config $args

	if {[llength $nameList] < $config(hashTableSize)} {
		set config(hashTableSize) [llength $nameList]
	}

	set maxLength 0
	set index -1
	foreach name $nameList {
		incr index
		set length [string length $name]
		set hash [expr {[zlib adler32 $name 0] % $config(hashTableSize)}]

		lappend indexesAtLength($length) $index
		lappend indexesAtHash($hash) $index

		if {$length > $maxLength} {
			set maxLength $length
		}
	}

	set maxIndexes 0
	foreach {hash indexes} [array get indexesAtHash] {
		set indexesCount [llength $indexes]

		if {$indexesCount > $maxIndexes} {
			set maxIndexes $indexesCount
		}
	}

	lappend outputHeader "${config(prefix)}long ${outCVarName}_idx;"
	lappend outputHeader "${config(prefix)}int ${outCVarName}_hash;"

	for {set hash 0} {$hash < $config(hashTableSize)} {incr hash} {
		if {[info exists indexesAtHash($hash)]} {
			set indexes $indexesAtHash($hash)
		} else {
			set indexes [list]
		}

		lappend indexes $invalidValue
		lappend outputHeader "${config(prefix)}static const long ${outCVarName}_hashTable_${hash}\[\] = \{"
		lappend outputHeader "${config(prefix)}\t[join $indexes {, }]"
		lappend outputHeader "${config(prefix)}\};"
	}

	lappend outputHeader "${config(prefix)}static const long * const ${outCVarName}_hashTable\[${config(hashTableSize)}\] = \{"

	for {set hash 0} {$hash < $config(hashTableSize)} {incr hash} {
		lappend outputHeader "${config(prefix)}\t${outCVarName}_hashTable_${hash},"
	}

	lappend outputHeader "${config(prefix)}\};"
	lappend outputBody "${config(prefix)}${outCVarName}_hash = Tcl_ZlibAdler32(0, (unsigned char *) ${cVarName}, ${cVarLength}) % ${config(hashTableSize)};"
	lappend outputBody "${config(prefix)}for (${outCVarName}_idx = 0; ${outCVarName}_idx <= ${maxIndexes}; ${outCVarName}_idx++) \{"
	lappend outputBody "${config(prefix)}\t${outCVarName} = ${outCVarName}_hashTable\[${outCVarName}_hash\]\[${outCVarName}_idx\];"
	lappend outputBody "${config(prefix)}\tif (${outCVarName} == $invalidValue) \{"
	lappend outputBody "${config(prefix)}\t\tbreak;"
	lappend outputBody "${config(prefix)}\t\}"
	lappend outputBody ""
	lappend outputBody "${config(prefix)}\tif (${config(validate)}) \{"
	lappend outputBody "${config(prefix)}\t\t${config(onValidated)}"
	lappend outputBody "${config(prefix)}\t\}"
	lappend outputBody "${config(prefix)}\}"

	return [dict create header [join $outputHeader "\n"] body [join $outputBody "\n"]]
}

package provide xvfs 1

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