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// FREEBIE
pull/1/head
Matthew Chen 8 years ago
parent 12de1aa90c
commit 89a04852df
1 changed files with 147 additions and 60 deletions
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169
Signal/src/network/GiphyDownloader.swift
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@ -12,7 +12,7 @@ enum GiphyRequestPriority {
enum GiphyAssetSegmentState: UInt {
case waiting
case active
case downloading
case complete
case failed
}
@ -24,7 +24,12 @@ class GiphyAssetSegment {
public let segmentStart: UInt
public let segmentLength: UInt
public let redundantLength: UInt
public var state: GiphyAssetSegmentState = .waiting
public var state: GiphyAssetSegmentState = .waiting {
didSet {
AssertIsOnMainThread()
}
}
private var datas = [Data]()
init(index: UInt,
@ -46,15 +51,27 @@ class GiphyAssetSegment {
}
public func append(data: Data) {
guard state == .downloading else {
owsFail("\(TAG) appending data in invalid state: \(state)")
return
}
datas.append(data)
}
public func mergeData(assetData: NSMutableData) {
guard state == .complete else {
owsFail("\(TAG) merging data in invalid state: \(state)")
return
}
// In some cases the last two segments will overlap.
// In that case, we only want to append the non-overlapping
// tail of the last segment.
var bytesToIgnore = Int(redundantLength)
var totalDataBytes: UInt = 0
for data in datas {
totalDataBytes += UInt(data.count)
if data.count <= bytesToIgnore {
bytesToIgnore -= data.count
} else if bytesToIgnore > 0 {
@ -66,14 +83,23 @@ class GiphyAssetSegment {
assetData.append(data)
}
}
guard totalDataBytes == segmentLength else {
owsFail("\(TAG) segment data length: \(totalDataBytes) doesn't match expected length: \(segmentLength)")
return
}
}
}
enum GiphyAssetRequestState: UInt {
// Does not yet have content length.
case waiting
// Getting content length.
case requestingSize
// Has content length, ready for downloads or downloads in flight.
case active
// Success
case complete
// Failure
case failed
}
@ -97,7 +123,6 @@ enum GiphyAssetRequestState: UInt {
var assetFilePath: String?
private var segments = [GiphyAssetSegment]()
private var assetData = NSMutableData()
public var state: GiphyAssetRequestState = .waiting
public var contentLength: Int = 0 {
didSet {
@ -122,9 +147,11 @@ enum GiphyAssetRequestState: UInt {
}
private func segmentSize() -> UInt {
let fileSize = UInt(contentLength)
guard fileSize > 0 else {
owsFail("\(TAG) rendition missing filesize")
AssertIsOnMainThread()
let contentLength = UInt(self.contentLength)
guard contentLength > 0 else {
owsFail("\(TAG) rendition missing contentLength")
requestDidFail()
return 0
}
@ -136,41 +163,46 @@ enum GiphyAssetRequestState: UInt {
let k10KB: UInt = 10 * 1024
let k1KB: UInt = 1 * 1024
for segmentSize in [k1MB, k500KB, k100KB, k50KB, k10KB, k1KB ] {
if fileSize >= segmentSize {
if contentLength >= segmentSize {
return segmentSize
}
}
return fileSize
return contentLength
}
private func createSegments() {
AssertIsOnMainThread()
let segmentLength = segmentSize()
guard segmentLength > 0 else {
return
}
let fileSize = UInt(contentLength)
let contentLength = UInt(self.contentLength)
var nextSegmentStart: UInt = 0
var index: UInt = 0
while nextSegmentStart < fileSize {
while nextSegmentStart < contentLength {
var segmentStart: UInt = nextSegmentStart
var redundantLength: UInt = 0
// The last segment may overlap the penultimate segment
// in order to keep the segment sizes uniform.
if segmentStart + segmentLength > fileSize {
redundantLength = segmentStart + segmentLength - fileSize
segmentStart = fileSize - segmentLength
if segmentStart + segmentLength > contentLength {
redundantLength = segmentStart + segmentLength - contentLength
segmentStart = contentLength - segmentLength
}
segments.append(GiphyAssetSegment(index:index,
let assetSegment = GiphyAssetSegment(index:index,
segmentStart:segmentStart,
segmentLength:segmentLength,
redundantLength:redundantLength))
redundantLength:redundantLength)
segments.append(assetSegment)
nextSegmentStart = segmentStart + segmentLength
index += 1
}
}
private func firstSegmentWithState(state: GiphyAssetSegmentState) -> GiphyAssetSegment? {
AssertIsOnMainThread()
for segment in segments {
guard segment.state != .failed else {
owsFail("\(TAG) unexpected failed segment.")
@ -184,26 +216,53 @@ enum GiphyAssetRequestState: UInt {
}
public func firstWaitingSegment() -> GiphyAssetSegment? {
AssertIsOnMainThread()
return firstSegmentWithState(state:.waiting)
}
public func firstActiveSegment() -> GiphyAssetSegment? {
return firstSegmentWithState(state:.active)
public func downloadingSegmentsCount() -> UInt {
AssertIsOnMainThread()
var result: UInt = 0
for segment in segments {
guard segment.state != .failed else {
owsFail("\(TAG) unexpected failed segment.")
continue
}
if segment.state == .downloading {
result += 1
}
}
return result
}
public func mergeSegmentData(segment: GiphyAssetSegment) {
guard segment.totalDataSize() > 0 else {
owsFail("\(TAG) could not merge empty segment.")
return
public func areAllSegmentsComplete() -> Bool {
AssertIsOnMainThread()
for segment in segments {
guard segment.state == .complete else {
return false
}
}
return true
}
public func writeAssetToFile(gifFolderPath: String) -> GiphyAsset? {
let assetData = NSMutableData()
for segment in segments {
guard segment.state == .complete else {
owsFail("\(TAG) could not merge incomplete segment.")
return
owsFail("\(TAG) unexpected incomplete segment.")
return nil
}
guard segment.totalDataSize() > 0 else {
owsFail("\(TAG) could not merge empty segment.")
return nil
}
segment.mergeData(assetData: assetData)
}
public func writeAssetToFile(gifFolderPath: String) -> GiphyAsset? {
guard assetData.length == contentLength else {
owsFail("\(TAG) asset data has unexpected length.")
return nil
@ -368,6 +427,8 @@ extension URLSessionTask {
static let sharedInstance = GiphyDownloader()
// A private queue used for download task callbacks.
//
// TODO:
private let operationQueue = OperationQueue()
var gifFolderPath = ""
@ -392,7 +453,8 @@ extension URLSessionTask {
configuration.urlCache = nil
configuration.requestCachePolicy = .reloadIgnoringCacheData
let session = URLSession(configuration:configuration,
delegate:self, delegateQueue:operationQueue)
delegate:self,
delegateQueue:operationQueue)
return session
}
@ -407,8 +469,6 @@ extension URLSessionTask {
// TODO: We could use a proper queue, e.g. implemented with a linked
// list.
private var assetRequestQueue = [GiphyAssetRequest]()
private let kMaxAssetRequestCount = 3
// private var activeAssetRequests = Set<GiphyAssetRequest>()
// The success and failure callbacks are always called on main queue.
//
@ -422,6 +482,7 @@ extension URLSessionTask {
if let asset = assetMap.get(key:rendition.url) {
// Synchronous cache hit.
Logger.verbose("\(self.TAG) asset cache hit: \(rendition.url)")
success(nil, asset)
return nil
}
@ -429,6 +490,7 @@ extension URLSessionTask {
// Cache miss.
//
// Asset requests are done queued and performed asynchronously.
Logger.verbose("\(self.TAG) asset cache miss: \(rendition.url)")
let assetRequest = GiphyAssetRequest(rendition:rendition,
priority:priority,
success:success,
@ -441,6 +503,8 @@ extension URLSessionTask {
public func cancelAllRequests() {
AssertIsOnMainThread()
Logger.verbose("\(self.TAG) cancelAllRequests")
self.assetRequestQueue.forEach { $0.cancel() }
self.assetRequestQueue = []
}
@ -449,12 +513,10 @@ extension URLSessionTask {
DispatchQueue.main.async {
assetSegment.state = .complete
// TODO: Should we move this merge off main thread?
assetRequest.mergeSegmentData(segment : assetSegment)
if assetRequest.areAllSegmentsComplete() {
// If the asset request has completed all of its segments,
// try to write the asset to file.
if assetRequest.firstWaitingSegment() == nil {
assetRequest.state = .complete
// Move write off main thread.
@ -510,6 +572,7 @@ extension URLSessionTask {
}
assetRequestQueue = assetRequestQueue.filter { $0 != assetRequest }
processRequestQueue()
}
// Start a request if necessary, complete asset requests if possible.
@ -562,17 +625,15 @@ extension URLSessionTask {
})
task.resume()
return
}
} else {
// Start a download task.
guard let assetSegment = assetRequest.firstWaitingSegment() else {
owsFail("\(self.TAG) queued asset request does not have a waiting segment.")
return
}
assetSegment.state = .active
assetRequest.state = .active
assetSegment.state = .downloading
var request = URLRequest(url: assetRequest.rendition.url as URL)
let rangeHeaderValue = "bytes=\(assetSegment.segmentStart)-\(assetSegment.segmentStart + assetSegment.segmentLength - 1)"
@ -582,9 +643,18 @@ extension URLSessionTask {
task.assetSegment = assetSegment
task.resume()
}
// Recurse; we may be able to start multiple downloads.
self.processRequestQueue()
}
}
private func handleAssetSizeResponse(assetRequest: GiphyAssetRequest, response: URLResponse?, error: Error?) {
guard error == nil else {
assetRequest.state = .failed
self.assetRequestDidFail(assetRequest:assetRequest)
return
}
guard let httpResponse = response as? HTTPURLResponse else {
owsFail("\(self.TAG) Asset size response is invalid.")
assetRequest.state = .failed
@ -617,19 +687,31 @@ extension URLSessionTask {
}
}
// Return the first asset request for which we either:
//
// * Need to download the content length.
// * Need to download at least one of its segments.
private func popNextAssetRequest() -> GiphyAssetRequest? {
AssertIsOnMainThread()
let kMaxAssetRequestCount: UInt = 9
let kMaxAssetRequestsPerAssetCount: UInt = 3
// Prefer the first "high" priority request;
// fall back to the first "low" priority request.
var activeAssetRequestsCount = 0
var activeAssetRequestsCount: UInt = 0
for priority in [GiphyRequestPriority.high, GiphyRequestPriority.low] {
for assetRequest in assetRequestQueue where assetRequest.priority == priority {
switch assetRequest.state {
case .waiting:
break
// This asset request needs its content length.
return assetRequest
case .requestingSize:
activeAssetRequestsCount += 1
// Ensure that only N requests are active at a time.
guard activeAssetRequestsCount < kMaxAssetRequestCount else {
return nil
}
continue
case .active:
break
@ -639,13 +721,18 @@ extension URLSessionTask {
continue
}
guard assetRequest.firstActiveSegment() == nil else {
activeAssetRequestsCount += 1
let downloadingSegmentsCount = assetRequest.downloadingSegmentsCount()
activeAssetRequestsCount += downloadingSegmentsCount
// Ensure that only N segment requests are active per asset at a time.
guard downloadingSegmentsCount < kMaxAssetRequestsPerAssetCount else {
continue
}
// Ensure that only N requests are active at a time.
guard activeAssetRequestsCount < self.kMaxAssetRequestCount else {
guard activeAssetRequestsCount < kMaxAssetRequestCount else {
return nil
}
guard assetRequest.firstWaitingSegment() != nil else {
/// Asset request does not have a waiting segment.
continue
}
return assetRequest

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