1 #include "quiche/http2/adapter/window_manager.h"
2
3 #include <utility>
4
5 #include "quiche/common/platform/api/quiche_bug_tracker.h"
6 #include "quiche/common/platform/api/quiche_logging.h"
7
8 namespace http2 {
9 namespace adapter {
10
DefaultShouldWindowUpdateFn(int64_t limit,int64_t window,int64_t delta)11 bool DefaultShouldWindowUpdateFn(int64_t limit, int64_t window, int64_t delta) {
12 // For the sake of efficiency, we want to send window updates if less than
13 // half of the max quota is available to the peer at any point in time.
14 const int64_t kDesiredMinWindow = limit / 2;
15 const int64_t kDesiredMinDelta = limit / 3;
16 if (delta >= kDesiredMinDelta) {
17 // This particular window update was sent because the available delta
18 // exceeded the desired minimum.
19 return true;
20 } else if (window < kDesiredMinWindow) {
21 // This particular window update was sent because the quota available to the
22 // peer at this moment is less than the desired minimum.
23 return true;
24 }
25 return false;
26 }
27
WindowManager(int64_t window_size_limit,WindowUpdateListener listener,ShouldWindowUpdateFn should_window_update_fn,bool update_window_on_notify)28 WindowManager::WindowManager(int64_t window_size_limit,
29 WindowUpdateListener listener,
30 ShouldWindowUpdateFn should_window_update_fn,
31 bool update_window_on_notify)
32 : limit_(window_size_limit),
33 window_(window_size_limit),
34 buffered_(0),
35 listener_(std::move(listener)),
36 should_window_update_fn_(std::move(should_window_update_fn)),
37 update_window_on_notify_(update_window_on_notify) {
38 if (!should_window_update_fn_) {
39 should_window_update_fn_ = DefaultShouldWindowUpdateFn;
40 }
41 }
42
OnWindowSizeLimitChange(const int64_t new_limit)43 void WindowManager::OnWindowSizeLimitChange(const int64_t new_limit) {
44 QUICHE_VLOG(2) << "WindowManager@" << this
45 << " OnWindowSizeLimitChange from old limit of " << limit_
46 << " to new limit of " << new_limit;
47 window_ += (new_limit - limit_);
48 limit_ = new_limit;
49 }
50
SetWindowSizeLimit(int64_t new_limit)51 void WindowManager::SetWindowSizeLimit(int64_t new_limit) {
52 QUICHE_VLOG(2) << "WindowManager@" << this
53 << " SetWindowSizeLimit from old limit of " << limit_
54 << " to new limit of " << new_limit;
55 limit_ = new_limit;
56 MaybeNotifyListener();
57 }
58
MarkDataBuffered(int64_t bytes)59 bool WindowManager::MarkDataBuffered(int64_t bytes) {
60 QUICHE_VLOG(2) << "WindowManager@" << this << " window: " << window_
61 << " bytes: " << bytes;
62 if (window_ < bytes) {
63 QUICHE_VLOG(2) << "WindowManager@" << this << " window underflow "
64 << "window: " << window_ << " bytes: " << bytes;
65 window_ = 0;
66 } else {
67 window_ -= bytes;
68 }
69 buffered_ += bytes;
70 if (window_ == 0) {
71 // If data hasn't been flushed in a while there may be space available.
72 MaybeNotifyListener();
73 }
74 return window_ > 0;
75 }
76
MarkDataFlushed(int64_t bytes)77 void WindowManager::MarkDataFlushed(int64_t bytes) {
78 QUICHE_VLOG(2) << "WindowManager@" << this << " buffered: " << buffered_
79 << " bytes: " << bytes;
80 if (buffered_ < bytes) {
81 QUICHE_BUG(bug_2816_1) << "WindowManager@" << this << " buffered underflow "
82 << "buffered_: " << buffered_ << " bytes: " << bytes;
83 buffered_ = 0;
84 } else {
85 buffered_ -= bytes;
86 }
87 MaybeNotifyListener();
88 }
89
MaybeNotifyListener()90 void WindowManager::MaybeNotifyListener() {
91 const int64_t delta = limit_ - (buffered_ + window_);
92 if (should_window_update_fn_(limit_, window_, delta) && delta > 0) {
93 QUICHE_VLOG(2) << "WindowManager@" << this
94 << " Informing listener of delta: " << delta;
95 listener_(delta);
96 if (update_window_on_notify_) {
97 window_ += delta;
98 }
99 }
100 }
101
102 } // namespace adapter
103 } // namespace http2
104