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Add buffer overrun concept to README

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Alex Kotov 2020-12-14 19:42:05 +05:00
parent 513fa40e7f
commit 841fd77530
Signed by: kotovalexarian
GPG key ID: 553C0EBBEB5D5F08
1 changed files with 35 additions and 6 deletions
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@ -141,13 +141,13 @@ Consumer pops more:
V
```
Producer pushes long message:
Producer pushes one short and one long message:
```
|
___ ___ ___ ___ ___ ___ ___ ___ _V_ ___
| | | |14 |15 | | |
|___|___|___|___|___ ___ ___ ___|___|___|
| | | |14 |15 |16 | | |
|___|___|___|___|___ ___ ___|___|___|___|
|
V
```
@ -157,10 +157,39 @@ Consumer pops one short and one long message:
```
|
___ ___ ___ ___ ___ ___ ___ ___ _V_ ___
| | | | | | | | | | |
| | | | | | | |16 | | |
|___|___|___|___|___|___|___|___|___|___|
|
V
|
V
```
Producer is in trouble now. He wants to send a long message, but he is
positioned at the second half of the buffer. The situation is complicated by the
fact that the size of the message may not be known in advance (stream-like
message queuing). To reduce the likelihood of it stalling due to lack of space,
it chooses whether to write to the current position or to the beginning of the
buffer, depending on where there is more free space at the moment. He compares
the following values:
* `Size of the buffer - Current position of the producer`
* `Current position of the consumer`
In our example, the second one is greater (remember that indices start with
zero):
```
10 - 8 = 2
_A_
/ \
| |
___ ___ ___ ___ ___ ___ ___ ___ _V_ _|_
| | | | | | | |16 | | |
|___|___|___|___|___|___|___|___|___|___|
| | |
| | V
\____________ __________/
V
7 - 0 = 7
```