"Shawn O. Pearce" <spearce@xxxxxxxxxxx> writes:
> This is the lowest buffer size we actually require to keep the
> client and server sides from deadlocking against each other.
Is this about the fetch-pack protocol where
(1) upload-pack shows what it has; fetch-pack keeps reading until it sees
a flush; then
(2) fetch-pack shows what it wants; upload-pack keeps reading; then
(3) fetch-pack sends a bunch of have's, followed by a flush; upload-pack
keeps reading and then responds with an ACK-continue or NAK, which
fetch-pack reads; this step continues zero or more times; and then
finally
(4) fetch-pack sends a bunch of have's, followed by a flush; upload-pack
keeps reading and then responds with an ACK, fetch-pack says done.
Where do you need "enough buffer"? The conversation looks very much "it's
my turn to talk", "now it's your turn to talk and I'll wait until I hear
from you", to me. I am puzzled.
> Also added documentation, and renamed the symbol to better match
> its real purpose; naming the lower threshold we can allow for a
> buffer.
>
> Signed-off-by: Shawn O. Pearce <spearce@xxxxxxxxxxx>
> ---
> .../jgit/transport/BasePackFetchConnection.java | 10 +++++++++-
> .../org/spearce/jgit/transport/TransportLocal.java | 2 +-
> 2 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackFetchConnection.java b/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackFetchConnection.java
> index eaa94bd..1d1b801 100644
> --- a/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackFetchConnection.java
> +++ b/org.spearce.jgit/src/org/spearce/jgit/transport/BasePackFetchConnection.java
> @@ -89,7 +89,15 @@
> */
> private static final int MAX_HAVES = 256;
>
> - protected static final int MAX_CLIENT_BUFFER = MAX_HAVES * 46 + 1024;
> + /**
> + * Amount of data the client sends before starting to read.
> + * <p>
> + * Any output stream given to the client must be able to buffer this many
> + * bytes before the client will stop writing and start reading from the
> + * input stream. If the output stream blocks before this many bytes are in
> + * the send queue, the system will deadlock.
> + */
> + protected static final int MIN_CLIENT_BUFFER = 2 * 32 * 46 + 4;
>
> static final String OPTION_INCLUDE_TAG = "include-tag";
>
> diff --git a/org.spearce.jgit/src/org/spearce/jgit/transport/TransportLocal.java b/org.spearce.jgit/src/org/spearce/jgit/transport/TransportLocal.java
> index cffdba1..428f73e 100644
> --- a/org.spearce.jgit/src/org/spearce/jgit/transport/TransportLocal.java
> +++ b/org.spearce.jgit/src/org/spearce/jgit/transport/TransportLocal.java
> @@ -175,7 +175,7 @@ InternalLocalFetchConnection() throws TransportException {
> // force the buffer to be big enough, otherwise it
> // will deadlock both threads.
> {
> - buffer = new byte[MAX_CLIENT_BUFFER];
> + buffer = new byte[MIN_CLIENT_BUFFER];
> }
> };
> out_w = new PipedOutputStream(out_r);
> --
> 1.6.3.48.g99c76
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