Performing multiple operations on same record in same transaction [duplicate]

Question

I am trying to do three operation using same record.

First Operation: Set ContentDocument isArchived field to false.

Second Operation: Grab contentdocument by calling REST API Endpoint.

Third Operation: Set ContentDocument isArchived field to true.

When I ran the logic by clicking on a button, isArchive was set to false but then got message, "you have uncommitted work pending. please commit or rollback before calling out". Also isArchive being false was also persisted in database. So, I had to manually set isArchived to true again. I tried to use savepoint and rollback but it gave me the same error.

Map<Id, ContentDocument> docMap = new Map<Id, ContentDocument>();
Savepoint sp;
List<ContentDocument> contDocs = new List<ContentDocument>();
public void doOperations() {
    operation1();
    operation3(); //operation2() called from operation3()
}


void operation1(){
//sp = Database.setSavepoint();
ContentDocument doc= [select id,IsArchived from ContentDocument where id = docMap.get(Id);
    if(doc.isArchived == true) {
        doc.isArchived = false;    
        update doc;
        contDocs.add(doc);
    }
}

void operation2(Id contentId) {
    //call restendpoint and retrieve contentDocument
}

void operation3(){
    operation2();
  // Database.rollback(sp); 
    for(integer i=0; i<contDocs.size(); i++){
        contDocs[0].isArchived = true;
        contDocs[1].isArchived = true;
    }
     update contDocs;
}

The doOperations is action method called from visualforce page. Is it possible to run all operations when a user clicks on a button.

I used rollbacks as well but could not solve the problem. Rollback and savepoint in above code is commented but even without commenting, could not resolve issue.

Edit: I know there are other question like this but i want to perform every operation synchronously. I cannot use future methods here.

Any idea/help on this.