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Use extended file attributes to store the record header #72

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2 changes: 2 additions & 0 deletions SPTPersistentCacheFramework/SPTPersistentCacheFramework.xcodeproj/project.pbxproj
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@
050076B31C7A4354000819B5 /* SPTPersistentCachePosixWrapper.h in Headers */ = {isa = PBXBuildFile; fileRef = 050076B11C7A4354000819B5 /* SPTPersistentCachePosixWrapper.h */; };
050076B41C7A4354000819B5 /* SPTPersistentCachePosixWrapper.m in Sources */ = {isa = PBXBuildFile; fileRef = 050076B21C7A4354000819B5 /* SPTPersistentCachePosixWrapper.m */; };
050076B51C7A4DC7000819B5 /* SPTPersistentCachePosixWrapper.m in Sources */ = {isa = PBXBuildFile; fileRef = 050076B21C7A4354000819B5 /* SPTPersistentCachePosixWrapper.m */; };
5EB3C5EB1CEA1B900091739E /* NSError+SPTPersistentCacheDomainErrors.h in Headers */ = {isa = PBXBuildFile; fileRef = DD1D238C1C7785A900D0477A /* NSError+SPTPersistentCacheDomainErrors.h */; };
9C9E707B1C790F0B00E1CBE6 /* SPTPersistentCacheObjectDescription.m in Sources */ = {isa = PBXBuildFile; fileRef = 9C9E70791C790F0B00E1CBE6 /* SPTPersistentCacheObjectDescription.m */; };
9C9E707C1C790F0B00E1CBE6 /* SPTPersistentCacheObjectDescription.h in Headers */ = {isa = PBXBuildFile; fileRef = 9C9E707A1C790F0B00E1CBE6 /* SPTPersistentCacheObjectDescription.h */; };
9C9E707D1C790F3700E1CBE6 /* SPTPersistentCacheObjectDescription.m in Sources */ = {isa = PBXBuildFile; fileRef = 9C9E70791C790F0B00E1CBE6 /* SPTPersistentCacheObjectDescription.m */; };
Expand Down Expand Up @@ -236,6 +237,7 @@
DD1D23851C77857E00D0477A /* SPTPersistentCache.h in Headers */,
DD1D23B51C7785AE00D0477A /* SPTPersistentCache+Private.h in Headers */,
DD1D23BB1C7785AE00D0477A /* SPTPersistentCacheRecord+Private.h in Headers */,
5EB3C5EB1CEA1B900091739E /* NSError+SPTPersistentCacheDomainErrors.h in Headers */,
DD1D23B31C7785AE00D0477A /* crc32iso3309.h in Headers */,
DD1D23BD1C7785AE00D0477A /* SPTPersistentCacheResponse+Private.h in Headers */,
C4EA65071C7A547000A6091A /* SPTPersistentCacheDebugUtilities.h in Headers */,
Expand Down
360 changes: 123 additions & 237 deletions Sources/SPTPersistentCache.m
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29 changes: 29 additions & 0 deletions Sources/SPTPersistentCacheHeader.m
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Original file line number Diff line number Diff line change
Expand Up @@ -23,9 +23,12 @@
#import "NSError+SPTPersistentCacheDomainErrors.h"

#include "crc32iso3309.h"
#include <sys/xattr.h>

const SPTPersistentCacheMagicType SPTPersistentCacheMagicValue = 0x46545053; // SPTF
const size_t SPTPersistentCacheRecordHeaderSize = sizeof(SPTPersistentCacheRecordHeader);
static NSString* const SPTPersistentCacheRecordHeaderAttributeName = @"com.spotify.cache";
static int const SPTPersistentCacheHeaderInvalidResult = -1;

_Static_assert(sizeof(SPTPersistentCacheRecordHeader) == 64,
"Struct SPTPersistentCacheRecordHeader has to be packed without padding");
Expand Down Expand Up @@ -69,6 +72,32 @@ SPTPersistentCacheRecordHeader SPTPersistentCacheRecordHeaderMake(uint64_t ttl,
return (SPTPersistentCacheRecordHeader *)data;
}

NSError* SPTPersistentCacheGetHeaderFromFileWithPath(NSString *filePath, SPTPersistentCacheRecordHeader *header)
{
memset(header, 0, SPTPersistentCacheRecordHeaderSize);
ssize_t size = getxattr([filePath UTF8String], [SPTPersistentCacheRecordHeaderAttributeName UTF8String], header, SPTPersistentCacheRecordHeaderSize, 0, 0);
if (size == SPTPersistentCacheHeaderInvalidResult) {
// try to load the legacy header. the fileHandle object uses file descriptor under the hood and responsible for closing it on deallocation.
NSFileHandle* fileHandle = [NSFileHandle fileHandleForReadingAtPath:filePath];
NSMutableData* rawData = [[fileHandle readDataOfLength:SPTPersistentCacheRecordHeaderSize] mutableCopy];
SPTPersistentCacheRecordHeader *legacyHeader = SPTPersistentCacheGetHeaderFromData(rawData.mutableBytes, rawData.length);
// If not enough data to cast to header, its not the file we can process
if (legacyHeader == NULL) {
return [NSError spt_persistentDataCacheErrorWithCode:SPTPersistentCacheLoadingErrorNotEnoughDataToGetHeader];
}
memcpy(header, legacyHeader, SPTPersistentCacheRecordHeaderSize);
}
return SPTPersistentCacheCheckValidHeader(header);
}

NSError* SPTPersistentCacheSetHeaderForFileWithPath(NSString *filepath, const SPTPersistentCacheRecordHeader *header) {
int res = setxattr([filepath UTF8String], [SPTPersistentCacheRecordHeaderAttributeName UTF8String], header, SPTPersistentCacheRecordHeaderSize, 0, 0);
if (res == SPTPersistentCacheHeaderInvalidResult) {
return [NSError spt_persistentDataCacheErrorWithCode:SPTPersistentCacheLoadingErrorFileAttributeOperationFail];
}
return nil;
}

int /*SPTPersistentCacheLoadingError*/ SPTPersistentCacheValidateHeader(const SPTPersistentCacheRecordHeader *header)
{
if (header == NULL) {
Expand Down
136 changes: 136 additions & 0 deletions Tests/SPTPersistentCacheHeaderTests.m
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,8 @@
#import <SPTPersistentCache/SPTPersistentCache.h>
#import "SPTPersistentCacheTypeUtilities.h"

static NSString* const SPTCacheRecordFileName = @"cache.record";


@interface SPTPersistentCacheHeaderTests : XCTestCase

Expand Down Expand Up @@ -101,4 +103,138 @@ - (void)testSPTPersistentCacheRecordHeaderMake
XCTAssertEqual(header.crc, SPTPersistentCacheCalculateHeaderCRC(&header));
}

- (void)testSPTPersistentCacheGetHeaderFromFileWithPath
{
// GIVEN
NSString *filePath = [NSTemporaryDirectory() stringByAppendingPathComponent:SPTCacheRecordFileName];
[self removeFileAtPath:filePath];
SPTPersistentCacheRecordHeader header = [self dummyHeader];
XCTAssertNil([self createRecordAtPath:filePath withHeader:&header]);

// WHEN
SPTPersistentCacheRecordHeader loadedHeader;
NSError* error = SPTPersistentCacheGetHeaderFromFileWithPath(filePath, &loadedHeader);

// THEN
XCTAssertNil(error);
XCTAssertEqual(header.reserved1, loadedHeader.reserved1);
XCTAssertEqual(header.reserved2, loadedHeader.reserved2);
XCTAssertEqual(header.reserved3, loadedHeader.reserved3);
XCTAssertEqual(header.reserved4, loadedHeader.reserved4);
XCTAssertEqual(header.flags, loadedHeader.flags);
XCTAssertEqual(header.magic, loadedHeader.magic);
XCTAssertEqual(header.headerSize, loadedHeader.headerSize);
XCTAssertEqual(header.refCount, loadedHeader.refCount);
XCTAssertEqual(header.ttl, loadedHeader.ttl);
XCTAssertEqual(header.payloadSizeBytes, loadedHeader.payloadSizeBytes);
XCTAssertEqual(header.updateTimeSec, loadedHeader.updateTimeSec);
XCTAssertEqual(header.crc, loadedHeader.crc);

[self removeFileAtPath:filePath];
}

- (void)testSPTPersistentCacheGetHeaderFromFileWithPathFailsWithError
{
// GIVEN
NSString *filePath = [NSTemporaryDirectory() stringByAppendingPathComponent:SPTCacheRecordFileName];

// WHEN
SPTPersistentCacheRecordHeader loadedHeader;
NSError* error = SPTPersistentCacheGetHeaderFromFileWithPath(filePath, &loadedHeader);

// THEN
XCTAssertNotNil(error);
}

- (void)testSPTPersistentCacheGetHeaderFromFileWithPathLegacy
{
// GIVEN
SPTPersistentCacheRecordHeader legacyHeader = [self dummyHeader];
NSData* payload = [[NSMutableData dataWithLength:legacyHeader.payloadSizeBytes] copy];
NSMutableData* rawData = [NSMutableData dataWithBytes:&legacyHeader length:SPTPersistentCacheRecordHeaderSize];
[rawData appendData:payload];
// create a record with legacy header (saved to the file with a payload).
NSString *filePath = [NSTemporaryDirectory() stringByAppendingPathComponent:SPTCacheRecordFileName];
[self removeFileAtPath:filePath];
XCTAssertTrue([[NSFileManager defaultManager] createFileAtPath:filePath contents:rawData attributes:nil]);

// WHEN
SPTPersistentCacheRecordHeader loadedHeader;
NSError* error = SPTPersistentCacheGetHeaderFromFileWithPath(filePath, &loadedHeader);

// THEN
XCTAssertNil(error);
XCTAssertEqual(legacyHeader.reserved1, loadedHeader.reserved1);
XCTAssertEqual(legacyHeader.reserved2, loadedHeader.reserved2);
XCTAssertEqual(legacyHeader.reserved3, loadedHeader.reserved3);
XCTAssertEqual(legacyHeader.reserved4, loadedHeader.reserved4);
XCTAssertEqual(legacyHeader.flags, loadedHeader.flags);
XCTAssertEqual(legacyHeader.magic, loadedHeader.magic);
XCTAssertEqual(legacyHeader.headerSize, loadedHeader.headerSize);
XCTAssertEqual(legacyHeader.refCount, loadedHeader.refCount);
XCTAssertEqual(legacyHeader.ttl, loadedHeader.ttl);
XCTAssertEqual(legacyHeader.payloadSizeBytes, loadedHeader.payloadSizeBytes);
XCTAssertEqual(legacyHeader.updateTimeSec, loadedHeader.updateTimeSec);
XCTAssertEqual(legacyHeader.crc, loadedHeader.crc);

[self removeFileAtPath:filePath];
}

- (void)testSPTPersistentCacheSetHeaderForFileWithPath
{
// GIVEN
NSString *filePath = [NSTemporaryDirectory() stringByAppendingPathComponent:SPTCacheRecordFileName];
[self removeFileAtPath:filePath];
SPTPersistentCacheRecordHeader header = [self dummyHeader];

// WHEN
NSError* error = [self createRecordAtPath:filePath withHeader:&header];

// THEN
XCTAssertNil(error);

[self removeFileAtPath:filePath];
}

- (void)testSPTPersistentCacheSetHeaderForFileWithPathFailsWithError
{
// GIVEN
NSString *filePath = [NSTemporaryDirectory() stringByAppendingPathComponent:SPTCacheRecordFileName];

// WHEN
SPTPersistentCacheRecordHeader loadedHeader;
NSError* error = SPTPersistentCacheSetHeaderForFileWithPath(filePath, &loadedHeader);

// THEN
XCTAssertNotNil(error);
}

#pragma mark - Private

- (NSError*)createRecordAtPath:(NSString*)filePath withHeader:(SPTPersistentCacheRecordHeader*)header
{
NSMutableData* data = [NSMutableData dataWithLength:header->payloadSizeBytes];

XCTAssertTrue([[NSFileManager defaultManager] createFileAtPath:filePath contents:data attributes:nil]);
return SPTPersistentCacheSetHeaderForFileWithPath(filePath, header);
}

- (void)removeFileAtPath:(NSString*)filePath
{
if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
NSError* error = nil;
[[NSFileManager defaultManager] removeItemAtPath:filePath error:&error];
XCTAssertNil(error);
}
}

- (SPTPersistentCacheRecordHeader)dummyHeader {
uint64_t ttl = 64;
uint64_t payloadSize = 400;
uint64_t updateTime = spt_uint64rint([[NSDate date] timeIntervalSince1970]);
BOOL isLocked = YES;

return SPTPersistentCacheRecordHeaderMake(ttl, payloadSize, updateTime, isLocked);
}

@end
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