A handle for streaming downloads.
Applications use this object to handle asynchronous streaming downloads. The application repeatedly calls Read() until it has received all the data it wants.
Constructors
AsyncReader(AsyncReader &&)
Move-only.
| Parameter | |
|---|---|
| Name | Description |
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AsyncReader &&
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AsyncReader(AsyncReader const &)
Move-only.
| Parameter | |
|---|---|
| Name | Description |
|
AsyncReader const &
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AsyncReader()
Creates a reader that always returns errors.
AsyncReader(std::unique_ptr< AsyncReaderConnection >)
Initialize a reader from its implementation class.
| Parameter | |
|---|---|
| Name | Description |
impl |
std::unique_ptr< AsyncReaderConnection >
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Operators
operator=(AsyncReader &&)
Move-only.
| Parameter | |
|---|---|
| Name | Description |
|
AsyncReader &&
|
| Returns | |
|---|---|
| Type | Description |
AsyncReader & |
|
operator=(AsyncReader const &)
Move-only.
| Parameter | |
|---|---|
| Name | Description |
|
AsyncReader const &
|
| Returns | |
|---|---|
| Type | Description |
AsyncReader & |
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Functions
Read(AsyncToken)
Retrieves more data from the object.
The returned future becomes satisfied when more data is available. Reading an object can fail even after the download starts, thus this function returns wraps the value with StatusOr<>. A successful end-of-stream is indicated by an invalid token.
Example (with coroutines)
future<std::int64_t> CountLines(AsyncReader reader, AsyncToken token) {
std::int64_t result = 0;
while (token.valid()) {
// Wait for next chunk and throw on error.
auto [payload, t_] = (co_await reader.Read(std::move(token))).value();
token = std::move(t_);
for (absl::string_view c : payload.contents()) {
result += std::count_if(c.begin(), c.end(), '\n');
}
}
co_return result;
}
| Parameter | |
|---|---|
| Name | Description |
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AsyncToken
|
| Returns | |
|---|---|
| Type | Description |
future< StatusOr< std::pair< ReadPayload, AsyncToken > > > |
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