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Merge pull request #343 from thekid/feature/io-buffer
Implement a limited in-memory buffer with filesystem overflow
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<?php namespace io\streams; | ||
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use io\{File, Folder}; | ||
use lang\{IllegalArgumentException, IllegalStateException}; | ||
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/** | ||
* Buffers in memory up until a given threshold, using the file system once | ||
* it's exceeded. | ||
* | ||
* @see https://github.com/xp-forge/web/issues/118 | ||
* @test io.unittest.BufferTest | ||
*/ | ||
class Buffer implements InputStream, OutputStream { | ||
private $files, $threshold; | ||
private $memory= ''; | ||
private $file= null; | ||
private $size= 0; | ||
private $pointer= 0; | ||
private $draining= false; | ||
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/** | ||
* Creates a new buffer | ||
* | ||
* @param io.Folder|io.Path|string $files | ||
* @param int $threshold | ||
* @throws lang.IllegalArgumentException | ||
*/ | ||
public function __construct($files, int $threshold) { | ||
if ($threshold < 0) { | ||
throw new IllegalArgumentException('Threshold must be >= 0'); | ||
} | ||
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$this->files= $files instanceof Folder ? $files->getURI() : (string)$files; | ||
$this->threshold= $threshold; | ||
} | ||
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/** Returns buffer size */ | ||
public function size(): int { return $this->size; } | ||
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/** Returns the underlying file, if any */ | ||
public function file(): ?File { return $this->file; } | ||
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/** Returns whether this buffer is draining */ | ||
public function draining(): bool { return $this->draining; } | ||
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/** | ||
* Write a string | ||
* | ||
* @param var $arg | ||
* @return void | ||
* @throws lang.IllegalStateException | ||
*/ | ||
public function write($bytes) { | ||
if ($this->draining) throw new IllegalStateException('Started draining buffer'); | ||
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$this->size+= strlen($bytes); | ||
if ($this->size <= $this->threshold) { | ||
$this->memory.= $bytes; | ||
return; | ||
} | ||
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if (null === $this->file) { | ||
$this->file= new File(tempnam($this->files, "b{$this->threshold}")); | ||
$this->file->open(File::READWRITE); | ||
$this->file->write($this->memory); | ||
$this->memory= null; | ||
} | ||
$this->file->write($bytes); | ||
} | ||
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/** @return void */ | ||
public function flush() { | ||
$this->file && $this->file->flush(); | ||
} | ||
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/** | ||
* Resets buffer to be able to read from the beginning | ||
* | ||
* @return void | ||
*/ | ||
public function reset() { | ||
$this->file ? $this->file->seek(0, SEEK_SET) : $this->pointer= 0; | ||
$this->draining= true; | ||
} | ||
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/** @return int */ | ||
public function available() { | ||
return $this->draining | ||
? $this->size - ($this->file ? $this->file->tell() : $this->pointer) | ||
: $this->size | ||
; | ||
} | ||
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/** | ||
* Read a string | ||
* | ||
* @param int $limit | ||
* @return string | ||
*/ | ||
public function read($limit= 8192) { | ||
if ($this->file) { | ||
$this->draining || $this->file->seek(0, SEEK_SET) && $this->draining= true; | ||
return (string)$this->file->read($limit); | ||
} else { | ||
$this->draining= true; | ||
$chunk= substr($this->memory, $this->pointer, $limit); | ||
$this->pointer+= strlen($chunk); | ||
return $chunk; | ||
} | ||
} | ||
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/** @return void */ | ||
public function close() { | ||
if (null === $this->file || !$this->file->isOpen()) return; | ||
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$this->file->close(); | ||
$this->file->unlink(); | ||
} | ||
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/** Ensure the file (if any) is closed */ | ||
public function __destruct() { | ||
$this->close(); | ||
} | ||
} |
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<?php namespace io\unittest; | ||
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use io\File; | ||
use io\streams\Buffer; | ||
use lang\{Environment, IllegalArgumentException, IllegalStateException}; | ||
use test\{Assert, Before, Test, Values}; | ||
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class BufferTest { | ||
const THRESHOLD= 128; | ||
private $temp; | ||
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#[Before] | ||
public function temp() { | ||
$this->temp= Environment::tempDir(); | ||
} | ||
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#[Test] | ||
public function can_create() { | ||
new Buffer($this->temp, self::THRESHOLD); | ||
} | ||
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#[Test] | ||
public function threshold_must_be_larger_than_zero() { | ||
Assert::throws(IllegalArgumentException::class, fn() => new Buffer($this->temp, -1)); | ||
} | ||
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#[Test, Values([1, 127, 128])] | ||
public function uses_memory_under_threshold($length) { | ||
$bytes= str_repeat('*', $length); | ||
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$fixture= new Buffer($this->temp, self::THRESHOLD); | ||
$fixture->write($bytes); | ||
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Assert::null($fixture->file()); | ||
Assert::equals($length, $fixture->size()); | ||
Assert::equals($bytes, $fixture->read()); | ||
} | ||
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#[Test, Values([129, 256, 1024])] | ||
public function stores_file_when_exceeding_threshold($length) { | ||
$bytes= str_repeat('*', $length); | ||
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$fixture= new Buffer($this->temp, self::THRESHOLD); | ||
$fixture->write($bytes); | ||
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Assert::instance(File::class, $fixture->file()); | ||
Assert::equals($length, $fixture->size()); | ||
Assert::equals($bytes, $fixture->read()); | ||
} | ||
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#[Test, Values([127, 128, 129])] | ||
public function read_after_eof($length) { | ||
$bytes= str_repeat('*', $length); | ||
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$fixture= new Buffer($this->temp, self::THRESHOLD); | ||
$fixture->write($bytes); | ||
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Assert::equals($length, $fixture->available()); | ||
Assert::equals($bytes, $fixture->read()); | ||
Assert::equals(0, $fixture->available()); | ||
Assert::equals('', $fixture->read()); | ||
} | ||
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#[Test, Values([127, 128, 129])] | ||
public function reset($length) { | ||
$bytes= str_repeat('*', $length); | ||
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$fixture= new Buffer($this->temp, self::THRESHOLD); | ||
$fixture->write($bytes); | ||
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Assert::equals($length, $fixture->available()); | ||
Assert::equals($bytes, $fixture->read()); | ||
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$fixture->reset(); | ||
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Assert::equals($length, $fixture->available()); | ||
Assert::equals($bytes, $fixture->read()); | ||
} | ||
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#[Test] | ||
public function cannot_write_after_draining_started() { | ||
$fixture= new Buffer($this->temp, self::THRESHOLD); | ||
$fixture->write('Test'); | ||
Assert::false($fixture->draining()); | ||
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$fixture->read(); | ||
Assert::true($fixture->draining()); | ||
Assert::throws(IllegalStateException::class, fn() => $fixture->write('Test')); | ||
} | ||
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#[Test] | ||
public function file_deleted_on_close() { | ||
$fixture= new Buffer($this->temp, 0); | ||
$fixture->write('Test'); | ||
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$fixture->close(); | ||
Assert::false($fixture->file()->exists()); | ||
} | ||
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#[Test] | ||
public function double_close() { | ||
$fixture= new Buffer($this->temp, 0); | ||
$fixture->write('Test'); | ||
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$fixture->close(); | ||
$fixture->close(); | ||
} | ||
} |