feat: server-side SDK #160

cwaldren-ld · 2023-07-06T17:51:04Z

This PR exists to verify the linting, compilation, and test CI steps for the work-in-progress Server-Side SDK.

This feature branch does not yet represent the finished product but rather an alpha. Once merged, additional work is needed to onboard to release please.

Moves the client's `ItemDescriptor` to internal where it can be shared, and gives it a generic parameter so it can hold flag rules/segments.

Augments event processor with context-key deduplication abilities using an LRU cache.

This PR extends our existing deserialization/serialization technique from the client-side SDK to the server-side SDK data model. Specifically, it adds deserialization for the segment structure. I've also introduced some helpers to make the logic less repetitive, and centralize some decisions (like what to do if a JSON field isn't present, or is null.) As background, the `tag_invoke` functions present in this PR are what allows the `boost::json` library to recursively deserialize complex structures. Here, I've added a couple new `tag_invokes` for bool, string, vector, etc. The special part is that they deserialize into `expected<type, error>` rather than the primitive directly; this allows us to return an error if the deserialization failed.

This PR builds on #153, extending the deserialization to flag data. I've added to the `PARSE_FIELD` macro to handle the following cases: 1. Parse a field where the zero-value is a valid part of the domain: `PARSE_FIELD`. In other words, if the field is omitted or null, it will be filled in with a default value. Most common scenario. 2. Like (1), but supply a default value in case the field is null or omitted: `PARSE_FIELD_DEFAULT`. 3. Parse a field that doesn't have a valid default value, and so is represented as an `optional`: `PARSE_CONDITIONAL_FIELD`. For example, the value `""` wouldn't be a valid default for a unique key. 4. Parse a field that must be present in the JSON data: `PARSE_REQUIRED_FIELD`. Usage of this should be rare; the test would be if the SDK is totally unable to function without this. To achieve this, I've made the `tag_invoke`s operate on `expected<optional<T>, JsonError`'s, instead of `expected<T, JsonError`. We could potentially revert that (and instead add a new enum case to `JsonError`), but I figure `optional` is a good representation of null/omitted. I think I need to actually try removing it to determine if it results in a better API. One thing lacking is better error messages - we use kSchemaFailure everywhere but we now have the ability to report exactly what was missing/wrong type, etc.

Adds in missing `Flag` model to the top-level `SDKDataSet`. Additionally, both the flag/segment fields now use use `PARSE_FIELD`, so we can get an empty `unordered_map` if they are missing.

Co-authored-by: Casey Waldren <[email protected]>

…174) Co-authored-by: Casey Waldren <[email protected]>

Co-authored-by: Casey Waldren <[email protected]>

Previously, context kind was an `std::string`. The requirement that it not be an empty string was enforced by parent data model deserializers. Now, we have a dedicated type-safe wrapper via`BOOST_STRONG_TYPEDEF`. The custom `tag_invoke` enforces the invariant so it's not possible to deserialize it inconsistently.

This commit contains the server-side evaluation engine and associated tests.

Adds a server-side Client object.

Current API of `EvaluationStack` is very easy to accidentally misuse because it takes a reference to its key argument. If the arg is destroyed, then we'll have a use-after-free.

Also fixes some style / const-correct issues that I found while documenting.

Adds a build for the server SDK, with various build fixes.

Adds a hello app for the Server-side SDK. Modifies the existing apps to fix CMake target name conflicts.

cwaldren-ld · 2023-10-20T21:18:20Z

libs/client-sdk/include/launchdarkly/client_side/data_source_status.hpp

-   public:
-    using DateTime = std::chrono::time_point<std::chrono::system_clock>;
-
+/**


Calling out as a theoretical breaking change.

In previous Client SDK, you could call IDataSourceStatusProvider::Status() and get back a class client_side::data_sources::DataSourceStatus.

Now, you get back a class common::data_sources::DataSourceStatusBase<DataSourceState>.

These classes should have the same API, but the concrete type has changed.

If the caller did:

auto status = sdk.DataSourceStatus().Status(); if (auto err = status.LastError()) { ... }

then this should compile without any changes. But if they did:

client_side::data_sources::DataSourceStatus status = sdk.DataSourceStatus().Status();

that's going to require a change.

We have some precedent for "non-major to fix a bug in the API definition" - but not sure if this counts.

Actually, this might be fine. The client_side::data_sources::DataSourceStatus is still present in the type system, it's just an alias for the common class.

It's (probably?) ABI breaking but we don't claim to support a stable C++ ABI.

The following code compiles without issue on the existing client, and the client in this PR:

client_side::data_sources::DataSourceStatus ds_status = client.DataSourceStatus().Status(); std::optional<client_side::data_sources::DataSourceStatus::ErrorInfo> last_err = ds_status.LastError(); client_side::data_sources::DataSourceStatus::DataSourceState state = ds_status.State(); client_side::data_sources::DataSourceStatus::DateTime date = ds_status.StateSince();

cwaldren-ld · 2023-10-20T21:34:26Z

I've reviewed all files, fixed a bunch of outstanding TODOs, and got this branch all caught up with main.

I'm feeling ready to merge ~~pending a backwards compatibility concern I've called out in comments.~~ (think I got myself confused on that one.)

🤖 I have created a release *beep* *boop* --- <details><summary>launchdarkly-cpp-client: 3.2.0</summary> ## [3.2.0](launchdarkly-cpp-client-v3.1.1...launchdarkly-cpp-client-v3.2.0) (2023-10-23) ### Features * server-side SDK ([#160](#160)) ([75eece3](75eece3)) ### Dependencies * The following workspace dependencies were updated * dependencies * launchdarkly-cpp-internal bumped from 0.2.0 to 0.3.0 * launchdarkly-cpp-common bumped from 0.4.0 to 0.5.0 </details> <details><summary>launchdarkly-cpp-common: 0.5.0</summary> ## [0.5.0](launchdarkly-cpp-common-v0.4.0...launchdarkly-cpp-common-v0.5.0) (2023-10-23) ### Features * server-side SDK ([#160](#160)) ([75eece3](75eece3)) </details> <details><summary>launchdarkly-cpp-internal: 0.3.0</summary> ## [0.3.0](launchdarkly-cpp-internal-v0.2.0...launchdarkly-cpp-internal-v0.3.0) (2023-10-23) ### Features * server-side SDK ([#160](#160)) ([75eece3](75eece3)) ### Dependencies * The following workspace dependencies were updated * dependencies * launchdarkly-cpp-common bumped from 0.4.0 to 0.5.0 </details> --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please). Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

🤖 I have created a release *beep* *boop* --- <details><summary>launchdarkly-cpp-server: 0.1.0</summary> ## 0.1.0 (2023-10-25) ### Features * server-side SDK ([#160](#160)) ([75eece3](75eece3)) ### Bug Fixes * allow for installing only the client or server SDK independently ([#269](#269)) ([fe08c3c](fe08c3c)) </details> --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please). Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

cwaldren-ld and others added 12 commits June 12, 2023 11:02

feat: add server-sdk subdirectory

c417579

chore: move ItemDescriptor to internal library (#151)

c985539

Moves the client's `ItemDescriptor` to internal where it can be shared, and gives it a generic parameter so it can hold flag rules/segments.

feat: update event processor to handle context key deduplication (#150)

420d7a2

Augments event processor with context-key deduplication abilities using an LRU cache.

chore: Merge branch 'main' into server-side

4f89b44

Merge branch 'main' into server-side

f38e038

feat: add Flag model to SDKDataSet (#159)

09d2bd6

Adds in missing `Flag` model to the top-level `SDKDataSet`. Additionally, both the flag/segment fields now use use `PARSE_FIELD`, so we can get an empty `unordered_map` if they are missing.

chore: Implement architecture diagram for data store. (#161)

8367305

fix: Add various missing headers. (#163)

2781af0

chore: Implement server data source architecture diagram. (#167)

90627f2

feat: Implement basic in-memory store and change handling. (#165)

f2d96a4

Co-authored-by: Casey Waldren <[email protected]>

cwaldren-ld marked this pull request as ready for review July 12, 2023 22:55

cwaldren-ld requested a review from a team July 12, 2023 22:55

cwaldren-ld marked this pull request as draft July 12, 2023 22:55

kinyoklion and others added 15 commits July 12, 2023 15:56

chore: Refactor to allow sharing data source status and IDataSource. (#…

3c12979

…174) Co-authored-by: Casey Waldren <[email protected]>

feat: Implement streaming data source. (#179)

08aaa66

Co-authored-by: Casey Waldren <[email protected]>

chore: Update data store updater use reference. (#181)

3692736

Merge branch 'main' into server-side

ceec434

feat: evaluation engine (#183)

e5992ef

This commit contains the server-side evaluation engine and associated tests.

feat: initial pass of server-side Client object (#176)

bb75d4b

Adds a server-side Client object.

feat: Add persistent store core interface. (#187)

674c343

fix: EvaluationStack should take ownership of key argument (#190)

0ead705

Current API of `EvaluationStack` is very easy to accidentally misuse because it takes a reference to its key argument. If the arg is destroyed, then we'll have a use-after-free.

feat: Add expiration tracker. (#188)

30d2e21

chore: add event processor architectural diagrams (#192)

213acbd

Also fixes some style / const-correct issues that I found while documenting.

feat: Serialize flags and segments. (#194)

0b29ea2

Merge branch 'main' into server-side

1f44309

feat: build server SDK in CI (#198)

a592e87

Adds a build for the server SDK, with various build fixes.

feat: hello-cpp-server (#202)

275bb66

Adds a hello app for the Server-side SDK. Modifies the existing apps to fix CMake target name conflicts.

cwaldren-ld added 7 commits October 20, 2023 09:21

use WriteMinimal where possible for writing JSON

880ab16

clang format

2c494ce

remove TODO about using initial reconnect delay (implemented)

64ab87d

remove/resolve some TODOs

ce9ae07

Merge branch 'main' into server-side

e217299

fix client-and-server-coexistence linking

a6a7456

update client/server readmes and put CMake options in toplevel readme

9597b29

cwaldren-ld force-pushed the server-side branch from 320ca84 to 9597b29 Compare October 20, 2023 20:21

revert change to client data source status state

943d07c

cwaldren-ld force-pushed the server-side branch from 197ed84 to 943d07c Compare October 20, 2023 20:38

remove unused evaluation detail API & remove implicit bool operator

8179eba

cwaldren-ld commented Oct 20, 2023

View reviewed changes

Merge branch 'main' into server-side

6f1aba6

cwaldren-ld marked this pull request as ready for review October 20, 2023 21:33

cwaldren-ld requested a review from a team October 20, 2023 21:33

cwaldren-ld added 4 commits October 20, 2023 15:39

Merge branch 'main' into server-side

1da898d

add some story links for todos

df4ef40

remove object slicing in asio_event_processor

d7453d3

remove useless inheritance usage in server-side events

17a9d38

cwaldren-ld enabled auto-merge (squash) October 23, 2023 17:49

kinyoklion approved these changes Oct 23, 2023

View reviewed changes

cwaldren-ld merged commit 75eece3 into main Oct 23, 2023
13 of 14 checks passed

cwaldren-ld deleted the server-side branch October 23, 2023 17:49

github-actions bot mentioned this pull request Oct 23, 2023

chore: release main #266

Merged

This was referenced Oct 23, 2023

chore: release main #271

Closed

chore: release main #273

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github-actions bot mentioned this pull request May 13, 2024

chore: release main #402

Closed

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feat: server-side SDK #160

feat: server-side SDK #160

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feat: server-side SDK #160

feat: server-side SDK #160

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